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A2 35 kW restrictor kit

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Baddi
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A2 35 kW restrictor kit

Post by Baddi on Wed 26 Oct 2016, 8:09 am

So I finally got my 35 kW restrictor kit which was not an airflow restriction in the rubber piece between the carbs and the cylinder head as I had expected. 

Instead, it is a small bracket that will prevent the throttle from being fully opened. The manufacturer is apparrently a german company named "Alpha Technik" and it cost me 1495 danish kroner, which is roughly the same as 180 british pound. Pretty comfortable saying that I mainly paid for the documentation rather than the actual restriction.

Pictures below but I've covered the last part of my frame no. on the documentation as I have no idea if it can be misused by anyone. Anyway, the documentation is from TÜV SUD and has my frame no. printed on every page as a watermark, so it's pretty specific for this bike. Smile 

I'll go see if I can mount it now. Smile







Tl;Dr of this thread: I had to split the carburators to get the restriction in place. In the process, I assembled stuff wrongly and I knocked loose the aluminum funnels in the carburator intake and the bike wouldn't run properly before they had been put back where they belong.


Last edited by Baddi on Thu 03 Nov 2016, 9:11 am; edited 1 time in total
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Re: A2 35 kW restrictor kit

Post by eternally_troubled on Wed 26 Oct 2016, 8:39 am

Hello!

These type throttle restrictions are actually better than the airflow restrictions: they are easier to remove when you need to remove it plus they don't mess with the fuelling of the bike in the same way as the air-flow restrictions.

I'd have thought that if you can remove the tank then you can fit one of these Smile

Good luck!
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Re: A2 35 kW restrictor kit

Post by Baddi on Wed 26 Oct 2016, 9:44 am

@eternally_troubled wrote:Hello!

These type throttle restrictions are actually better than the airflow restrictions:  they are easier to remove when you need to remove it plus they don't mess with the fuelling of the bike in the same way as the air-flow restrictions.

I'd have thought that if you can remove the tank then you can fit one of these Smile

Good luck!

Yep, they are better for the airflow/fuel mixture in the sense that the carburator and intake is allowed to function as designed. 

But I think "as designed" is pretty far from where this bike is now unfortunately. When I got the tank off, the crankcase ventilation hose (from the cylinder head to the air filter box) was not connected and some secondary air filter was completely trashed as seen on the picture below. To make matters even worse there were signs of an oil leak at the oil filter and to top it off, the blinkers blink 3 times per second rather than the 1-2 times per second the law perscribes and I can't get my hands on the original blinkers before friday. 
Doesn't look like I'll get it approved within this week. Sad 

Anyway, the motorcycle is apart now and I just have to get the carburators off and install the restriction. And figure out where to put the approval sticker. 


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Re: A2 35 kW restrictor kit

Post by Baddi on Wed 26 Oct 2016, 10:24 am

I had to stop and pack up before the restriction was installed in order to be able to get to class in time. I simply couldn't get to those two screws while the carburators were on the engine. The best I could do was to get to the top screw at an odd angle and since these screws are Japanese Industry Standard and not Phillips screw heads, I was even less comfortable unscrewing them at an odd angle.

Am I really supposed to dismount the carburators and seperate them in order to get to those two screws?

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Re: A2 35 kW restrictor kit

Post by eternally_troubled on Wed 26 Oct 2016, 6:45 pm

You are right, you don't need to split the carbs to put this on.  You just need the correct type of screwdriver to undo those screws.

If you had a socket set something like this you can use it like a 90-degree screwdriver, which might help.

Or you could get one of these bendy things.

Or one of these 90-degree screwdriver.

I guess that you can probably find somewhere that sells one or other of these things (or similar) in Denmark.

Definitely *don't* take anything apart or force anything (sorry if you know this already) - I think it's just a matter of finding the correct tool!
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Re: A2 35 kW restrictor kit

Post by Baddi on Wed 26 Oct 2016, 8:23 pm

That makes sense! Very Happy 
I hadn't thought of those before as I have never needed them before.
I've borrowed a bendy screwdriver from a friend, but won't have time to use it before friday. I'll let you know when I get it installed. Smile
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Re: A2 35 kW restrictor kit

Post by Baddi on Fri 28 Oct 2016, 10:04 pm

I ended up having to separate the carbs to get the the bracket. 
The flexible screwdriver was too big and not flexible enough to get in between the two carburators. We then tried to use only the bits and press them into the screws and use a wrench to turn them, but they fell down and were lost for quite some time until the carbs and air filter were off and we could see properly.
Pictures of the carburators separately as a proof. For some reason, I took the picture just before I installed the restriction and not just after, which would have made sense, so you'll have to wait for those pictures until tomorrow. 

I marked how much the throttle moved with and without the restriction. The mark to the right is when the throttle is completely unactivated and the next mark is when the throttle has been activated just enough to eliminate free-play. The third mark is the maximum throttle position with the restriction and the far left mark is the maximum throttle position without the restriction. I was pretty surprised that that little movement of the throttle is enough to remove 10 horsepower. 



I have to go out and continue work on the bike tomorrow again though, because after reassembling the motorcycle, I found a small spring on the ground below the bike, which must have fallen off without me noticing it. I am pretty sure that it is no. 15 "Throttle linkage spring" on the exploded view drawing below. After a short drive of 20 meters to check that it could run, the rpm would rise from idle without me touching the throttle. I guess that either the spring is important or I forgot to tighten something so there's air entering somewhere. 




I really should stop thinking that I can finish something on the bike before it gets dark. It is shit to work in the dark and the girlfriend wasn't very happy to have to light a bicycle light for me for an hour.




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Re: A2 35 kW restrictor kit

Post by stormbringer on Sat 29 Oct 2016, 9:34 am

Oh boy, you ARE getting stuck in - right away!

I like your approach; methodical (apart from the spring gone missing). Now, once it's all been reassembled, it will be interesting to find out if the carbs have been thrown off-balance.
I guess the engine will 'limp' if so - more than would be caused by its 180 degree crank-design.

On the 'net I've found this info regarding 180 degree crank parallel-twins. It tells you that the 180-degree design has uneven firing order, low pumping losses, requires two carbs and separate ignition systems and that a balancing shaft is preferable. In this context, I'm referring to the uneven firing order of 180-540 which should have you hearing "pof-pof----pof-pof---"
Still, improperly balanced carbs will produce less power as one cylinder will produce less than the other - not what you'd want.
There's a nice animation showing the differences between crank design here.
While you're at it: Try to loosen the front engine mounting bolt. See if you can turn it. This bolt tends to get stuck, and if yours has not yet seized, take the opportunity to grease it up properly.
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Re: A2 35 kW restrictor kit

Post by Baddi on Sat 29 Oct 2016, 11:34 am

@stormbringer wrote:Oh boy, you ARE getting stuck in - right away!

I like your approach; methodical (apart from the spring gone missing). Now, once it's all been reassembled, it will be interesting to find out if the carbs have been thrown off-balance.
I guess the engine will 'limp' if so - more than would be caused by its 180 degree crank-design.

On the 'net I've found this info regarding 180 degree crank parallel-twins. It tells you that the 180-degree design has uneven firing order, low pumping losses, requires two carbs and separate ignition systems and that a balancing shaft is preferable. In this context, I'm referring to the uneven firing order of 180-540 which should have you hearing "pof-pof----pof-pof---"
Still, improperly balanced carbs will produce less power as one cylinder will produce less than the other - not what you'd want.
There's a nice animation showing the differences between crank design here.
While you're at it: Try to loosen the front engine mounting bolt. See if you can turn it. This bolt tends to get stuck, and if yours has not yet seized, take the opportunity to grease it up properly.

We'll move a bit off topic now, but that's okay some times as I think it is interesting to think of how the stresses in the components will change if we mess about with the engine. Very Happy 

On the subject of throwing off the balance of the carburators:
If you have more power on one cylinder than the other, it goes more towards stressing the components more like a 1-cylinder engine than a 2 cylinder engine.
In the days before computer simulations and computerized simulations, a usage factor depending on the power source and the type of appliance was multiplied to the torque or force to take load/stress spikes into account. This usage factor could be 1,75 for a single cylinder and 1,5 for a multi-cylinder engine, so if one cylinder is not producing power and the driver want 20 hp output from the motor, he would need to get all of that power from one cylinder instead of two and thus the stresses are higher as the usage factor is higher. 
Also, since 2 cylinders still have some time between firing compared to a motor with four or more cylinders, the usage factor should be somewhere between the single cylinder and the multiple cylinder factor. 
I'm not convinced that this would reduce the life of the motor components significantly though, because I suspect that the components are dimensioned for safety against fatigue stress at the highest possible load which would be much higher with both cylinders operating than with only one operating, even though the usage factor (stress spikes) are higher with only one cylinder operating. Smile 


On the subject of crankshaft degrees:
As we discussed a bit in 2013 with the piston speed calculation spreadsheet, the piston speeds and accelerations will be very high as the rpm goes up. I've done some rough calculations and I'm convinced that, at the rpm at a couple of thousands rpm and above, the stresses of accelerating and decellerating the pistons are greater than the stresses due to the combustion pushing on the piston. Smile 
If we assume that accelerating and decelerating the pistons are the main source of stresses on the bearing and crankshaft, the forces on the crankshaft bearings should pretty much cancel out on the 180 deg. crankshaft because the forces of the two pistons are the opposite, of the same size and alternating. 
On the 360 deg. crankshaft the forces from the pistons are in the same direction, so the force on the bearings are double that of one cylinder and alternating direction every 180 deg. as a 2xsine-curve, so the peak is double that of 1 cylinder.
On the 270 deg. crankshaft, one piston will be at maxium velocity when the other is at 0 velocity and thus one will constantly help the other accelerate the other. The force on the bearings will be alternating as cosine+sine, which means that the peak is sqrt(2) (1,414) times the force of a single cylinder. 

Then the other part which is the torque on the part of the crankshaft that goes to the flywheel and the size of the flywheel. 
As both the pistons of the 180 deg. and the 360 deg design are at zero and max velocity at the same time, the flywheel will have to deliver all of the torque required to accelerate and decellerate the pistons, which requires a larger flywheel and a stronger crankshaft to the flywheel.
With the 270 deg. design, one piston will be decelerating as the other is accelerating and thus the flywheel won't have to deliver the torque to accelerate and decelerate the pistons and the flywheel should be able to be made smaller and the connection to the flywheel can be lighter. 

When choosing between these three designs, the stresses on the bearings and the flywheel are compromises that has to be made, but as the wikipedia site you linked to suggests, the vibrations due to the combustion cycle might be more of a factor, but I'm not very good at structural vibrations, so I can't really say much about that. 
Anyway, I can't find a single good reason in the engine itself to choose 360 deg. design. 

Enough off-topic, I have to get back out to the motorcycle and figure out where the spring should be put and why the motor was wierd last night. Very Happy
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Re: A2 35 kW restrictor kit

Post by Baddi on Sat 29 Oct 2016, 3:12 pm

I found the spring. I also noticed that it was visible on the lower left corner of one of the pictures from last night.



But you were right. My problems were in the syncronisation due to wrong assembly. On the picture below, it is seen that one of the carburators are open when the other is closed. 



I also found that one of the earlier owners broke the adjustment screw on the left carburator... I guess I'll need a new of those.



Here is the space where the spring is supposed to be and also is seen the wrong assembly of the carbs, as the throttle thing for the left carb is not put in the wrong place.



On the next picture, it is all assembled correctly and the throttle thing for the left carb is in its correct position.



Here, we see that the throttle linkage spring is in between the throttles for the left and right carb. I can't find a reason for it to be there, but now it is. Also, here you can see that I put a blue mark on the syncronisation screw to be able to put it back in the same position afterwards. This picture was before the syncronisation screw was turned 5 rotations down, which was how much I had unscrewed it. Wink 



And now, both carburators are equally closed. 



But what is that small tube supposed to be connected to? In the manual, it is named breather joint, but I can't find any loose tubes that should connect to it...



In other news: now it won't start and I don't have a spark plug tool that is long enough to be able to get the plugs out and check if there is spark.
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Re: A2 35 kW restrictor kit

Post by Baddi on Sat 29 Oct 2016, 5:17 pm

Still can't get the engine to start. 
The starter motor spins the engine, theres gasoline in the carburators and there's a spark on the spark plug caps.

I'm pretty much convinced that the engine is simply flooded from having one carb fully open while the other was closed. Normally I would look at the spark plug and let it dry if it was wet, but as all of my former engines has been single cylinder air cooled, I don't have a spark plug tool that is long enough to reach the spark plugs on the CB 500.  Neutral

Edit: DOH, I just realised that the long socket I have could probably fit over the spark plug so I could use my normal wrench to get the spark plugs loose, but now it is too dark to do so.  Neutral
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Re: A2 35 kW restrictor kit

Post by ashcroc on Sat 29 Oct 2016, 9:50 pm

There's a plug socket in the OE tool kit which lives in the tail section if you're lucky enough to have it.
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Re: A2 35 kW restrictor kit

Post by Baddi on Sat 29 Oct 2016, 11:16 pm

@ashcroc wrote:There's a plug socket in the OE tool kit which lives in the tail section if you're lucky enough to have it.



Nope, there wasn't. On the other hand, there were no less than three (3) tools to prestiffen the springs of the rear shock absorbers. Smile
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Re: A2 35 kW restrictor kit

Post by spanner monkey on Sun 30 Oct 2016, 11:03 am

interesting topic. I have just removed the restrictor on my 2002. it was the air flow type, and considering the amount of messing you had with these carbs Id say its easier to fit/remove the washer into the inlet manifold. I never needed the restrictor, it was on the bike when I got it, so took it out a couple of weeks ago. ridden it for four year like it, and there was no issue with the carb not being allowed to operate properly, as it just manages throttle not mixture in any way. the plugs were in A1 condition which is telling of the fuel air mix running through even with the restrictor fitted. anyway, either method ok, but that throttle block system seems a right faf. the breather pipe you mentioned just runs to the underside of the bike, doesnt attach to anything.
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Re: A2 35 kW restrictor kit

Post by eternally_troubled on Sun 30 Oct 2016, 7:44 pm

Wow - that's an extreme way to balance your carbs Smile

Any luck getting it to start?  Did you get the plugs out?
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Re: A2 35 kW restrictor kit

Post by Baddi on Mon 31 Oct 2016, 9:15 am

Yeah, I got the plugs out, but not as I had expected. The socket I had for my wrench did not fit into the hole, so I ended up doing a complete hacker solution:The wrench extender kind of fit into the spark plug tool I had from my air cooled machines and I could get the plugs out like that.






The plugs turned out to be covered in so much soot that they couldn't produce a spark, so I bought some new plugs and put in. But it still wouldn't start.  Evil or Very Mad 

After getting really bummed out by having spent all of our money on a bike that wouldn't start, we went to buy grocery shopping and upon returning, I tried one last time and it fired! Yay! Very Happy
I guess it just wanted me to tickle its carbs and decided to try and keep the game going as long as it could but decided that enough were enough when I got really mad at it.  Laughing
 
We went for a small trip and it worked nicely, so we got the fairings back on so it can go to be approved today.
The only thing that's odd is that the temperature meter got all the way up to the middle today when driving to school, which it didn't do when I drove the motorcycle home after buying it, so I'm wondering if I might have lost a significant amount of cooling water when taking the carbs off and on a million times. Smile 

Before I remove the tape where I marked how much the throttle can turn with and without the restriction, would you be interested in knowing how many degrees of twisting it restricts? Smile
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Re: A2 35 kW restrictor kit

Post by Jameshambleton on Mon 31 Oct 2016, 9:42 am

Have you remembered to connect all the hoses correctly back into the carbs, as the coolant goes around the carbs to warm them up as it helps prevent carb icing.
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Re: A2 35 kW restrictor kit

Post by Baddi on Mon 31 Oct 2016, 10:24 am

@Jameshambleton wrote:Have you remembered to connect all the hoses correctly back into the carbs, as the coolant goes around the carbs to warm them up as it helps prevent carb icing.





I'm pretty sure I did, but I'll check that once more! Wink

Checked it and they were all connected where they should be and the coolant hose to the carb got pretty hot too, so I know that it is circulating. Smile


Last edited by Baddi on Mon 31 Oct 2016, 4:51 pm; edited 2 times in total
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Re: A2 35 kW restrictor kit

Post by Baddi on Mon 31 Oct 2016, 4:50 pm

It only fires on one cylinder now and it doesn't do that very stably.

Is it possible that misbalanced carbs can cause so much soot buildup on the spark plugs that it will only fire on one cylinder?



I've been thinking a bit about how i might have underestimated the importance of carburator balancing after being in single cylinder land for 6 years. I used to ride a 50cc scooter with aftermarket fuel injection and wideband lambda sensor and could tell that it would combust pretty much any mixture i'd throw at it. I started at a mixture of 6:1 (14,7:1 being stoich) and leaned it out to the right mixture and even had it at about 18:1 at mid-throttle to save fuel but whenever I got too rich or too lean, it just wouldn't accelerate or run properly. 

So what is different that I did not think of? Well, after thinking a lot about it, I've come to the conclusion that with two cylinders, one cylinder could be running so rich that it wouldn't be able to sustain the rpm, but the other cylinder is forcing it to run and keep sucking in a bad mixture until it is so sooted that it can no longer produce a spark. Smile 
I guess it makes sense now and what I should do to get the motorcycle back and running is to clean the spark plugs and then balance and tune the carbs.
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Re: A2 35 kW restrictor kit

Post by stormbringer on Mon 31 Oct 2016, 8:04 pm

@Baddi wrote:It only fires on one cylinder now and it doesn't do that very stably.

Is it possible that misbalanced carbs can cause so much soot buildup on the spark plugs that it will only fire on one cylinder?
Bugger...

Misbalance -> soot: I don't think so. Given carbs are OK, it's not the fuel/air mix that's off, and I wouldn't expect a cylinder 'falling behind' to foul up - it's just kinda tagging along, and with a full spark any combustibles should get ignited properly anyway.

You said it has been running OK for a while, but no longer does that. The uneven firing hints me into thinking one clogged-up carb or one faulty/lazy coil. You have had those carbs out several times and who knows what crud may have come undone in the process.

I've never had my carbs out - other people can tell you more about  their experiences in that respect.

Spark: You did clean up the plugs properly and install them without greasing/fingering up the porcelain stems? At 25 kV, cleanliness is important! I ask because I've not had this issue (yet) and I always use clean kitchen roll when handling the plugs, degrease/siliconise the HT-lead rubbers and assemble only when everything is spotless and dry. You'd be surprised how far those 25 kV can creep and discharge...

The upside is that when the HT-cables are done up right, the mechanical design leaves little chance for moisture to creep in and ruin the fun bit; wroom...


What I'm trying to say is; go slow to go fast. You'll get there. Be your methodical you and advance through the checklist. Spark, air, gas, ratio, timing. With you having poked the fuel supply system, I'd focus on that; none of the other components have been altered or touched in any significant way. New plugs should be an improvement. But new parts are untested parts... Have you identified the missing cylinder? If not, carefully remove one lead and you will know if it's that side. Check the plug for fouling, no-spark etc. Something's not right...

Carb balancing? Carbtune. 59 GBP + p&p; wanna share?
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Re: A2 35 kW restrictor kit

Post by Baddi on Mon 31 Oct 2016, 8:28 pm

@stormbringer wrote:
@Baddi wrote:It only fires on one cylinder now and it doesn't do that very stably.

Is it possible that misbalanced carbs can cause so much soot buildup on the spark plugs that it will only fire on one cylinder?
Bugger...

Misbalance -> soot: I don't think so. Given carbs are OK, it's not the fuel/air mix that's off, and I wouldn't expect a cylinder 'falling behind' to foul up - it's just kinda tagging along, and with a full spark any combustibles should get ignited properly anyway.

You said it has been running OK for a while, but no longer does that. The uneven firing hints me into thinking one clogged-up carb or one faulty/lazy coil. You have had those carbs out several times and who knows what crud may have come undone in the process.

I've never had my carbs out - other people can tell you more about  their experiences in that respect.

Spark: You did clean up the plugs properly and install them without greasing/fingering up the porcelain stems? At 25 kV, cleanliness is important! I ask because I've not had this issue (yet) and I always use clean kitchen roll when handling the plugs, degrease the rubbers and assemble only when everything is spotless and dry. You'd be surprised how far those 25 kV can creep and discharge...

The upside is that when the HT-cables are done up right, the mechanical design leaves little chance for moisture to creep in and ruin the fun bit; wroom...


What I'm trying to say is; go slow to go fast. You'll get there. Be your methodical you and advance through the checklist. Spark, air, gas, ratio, timing. With you having poked the fuel supply system, I'd focus on that; none of the other components have been altered or touched in any significant way. New plugs should be an improvement. But new parts are untested parts... Have you identified the missing cylinder? If not, carefully remove one lead and you will know if it's that side. Check the plug for fouling, no-spark etc. Something's not right...
Yeah, both the cylinders ran last night and this morning, but when I was about to leave the university to go to get it approved it first felt sluggish and then died after 200 meters and couldn't get started. I went and got a fresh battery and got it started and after idling for a while it finally was able to idle and accelerate properly as both cylinders were active. After driving a kilometer or two (and stopping and accelerating for at least 5 traffic lights, one cylinder stopped and the motorcycle died. 30 seconds later, it were able to run for another couple of hundred meters and then dying.
After a bit, I got it to run again, although only on 1 cylinder and I had to keep some throttle to prevent it from stalling. After 2 more kilometers it died again and after waiting a bit, I got it to run on 1 cylinder and get home. 

The spark plugs I installed were clean, but I guess that at least one of them might be full of soot and preventing a spark. 

The cause must be something I have done, as you said. I'm thinking the adjustment of the carbs or that those aluminum funnels in the intake might have come loose.
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Re: A2 35 kW restrictor kit

Post by stormbringer on Mon 31 Oct 2016, 8:35 pm

@Baddi wrote:The cause must be something I have done, as you said. I'm thinking the adjustment of the carbs or that those aluminum funnels in the intake might have come loose.
Out of curiosity; have you tried running the bike with the gas tank cap open? Running for a while, then stuttering and eventually cutting out sounds like fuel starvation, and that may very well come out of a blocked tank venting hose. Pop the tank cap and see if that helps...

The venting hose is known to become squished on gas tank reinstall.

Aluminium funnels? Anyone? I'm in the dark here...


Last edited by stormbringer on Mon 31 Oct 2016, 8:51 pm; edited 1 time in total
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Re: A2 35 kW restrictor kit

Post by stormbringer on Mon 31 Oct 2016, 8:46 pm

@Baddi wrote:...it first felt sluggish and then died after 200 meters and couldn't get started. I went and got a fresh battery and got it started and after idling for a while it finally was able to idle and accelerate properly as both cylinders were active. After driving a kilometer or two (and stopping and accelerating for at least 5 traffic lights, one cylinder stopped and the motorcycle died. 30 seconds later, it were able to run for another couple of hundred meters and then dying.
Crud circulating carb bowl(s), on occasion getting sucked into the petrol intake, then on engine stall drawn away by gravity, enabling the bike to start again?
Vacuum, caused by blocked tank vent hose?
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Re: A2 35 kW restrictor kit

Post by Baddi on Mon 31 Oct 2016, 8:53 pm

@stormbringer wrote:



@Baddi wrote:The cause must be something I have done, as you said. I'm thinking the adjustment of the carbs or that those aluminum funnels in the intake might have come loose.






Out of curiosity; have you tried running the bike with the gas tank cap open? Running for a while, then stuttering and eventually cutting out sounds like fuel starvation, and that may very well come out of a blocked tank venting hose. Pop the tank cap and see if that helps...

The venting hose is known to become squished on gas tank reinstall.

Aluminium funnels? Anyone? I'm in the dark here...



I'll try and open the tank and then drive. Smile 
But I haven't noticied any venting hose from the fuel tank. Where should it be? 

About the aluminum funnels, I couldn't find anything on this forum by searching on funnel, intake or tract, so I guess it might not have been something that other people have had problems with. Anyway, I found this picture on the internet:



Behind the edge of the tract is the static air pressure tubes where the air for the idle system, the choker system and the high pressure (static pressure) part of the venturi is. 
I guess that if the tract is loose, the air pressure might be wrong and the carburator might not work properly, i guess. The black plastic part with the four screws visible on this side of the carburator is supposed to hold the aluminum funnels in place but I knocked them loose with the air filter box. Smile

Found another picture: Part no. 19.



Last edited by Baddi on Mon 31 Oct 2016, 8:56 pm; edited 1 time in total
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Re: A2 35 kW restrictor kit

Post by Beresford on Mon 31 Oct 2016, 8:55 pm

@stormbringer wrote:Aluminium funnels? Anyone? I'm in the dark here...



Carburettor bell-mouths are aluminium
AKA ram stacks, carb trumpets.

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Re: A2 35 kW restrictor kit

Post by Sponsored content


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