Problem after fitting mcct's

[VTR_Stormer]

Hi guys,

I have recently fitted my manual cct's and have ridden it once. It seemed to working fine, sounded ok and had plenty of power. I left it a few days and then went to ride it one morning to work and it sounded terrible, no power, coughing and spluttering and backfiring. Wouldn't rev past 2500rpm. Thinking it was timing related I pulled it down again and checked both front and back cylinders and they are both fine, lined up with the related lines as stated in forum instructions but yet these issues.

I have checked all the hoses etc just in case but now when you blip the throttle to approx 2500 there is a click ( fairly loud ) from the front pot and the revs die off and then return to idle. You do it again and same thing. The bike idles ok and is stable at 1200rpm. Do you guys have any ideas and what to look for?
Thanks in advance

[darkember]

If the timing is set good & you seem to be clear in that area. There has been a little confusion on cam chain tension with the 5-7mm rule of thumb which I believe to have been settled.

When measuring this slack it means in one direction only.

To me it sounds like something in the carbs, there was a recent post on the sliders rattling, something to look at as the carbs have been displaced. Someone on here will be able to link the thread as I cannot find it.

[Stratman]

You have put the vacuum pipe on the right pipe from the petcock haven't you? The one on the side, not on the bottom?

[VTR_Stormer]

You have put the vacuum pipe on the right pipe from the petcock haven't you? The one on the side, not on the bottom?

Yes all hoses are on correctly.,but that doesn't explain the loud click

[Wicky]

What procedure did you follow for installing them? i.e. the one here in the workshop knowledgebase or Haynes manual. And which type of manual CCT?

Where are you based as someone might be nearby to give it a second once-over. Have you pics of the where you've repositioned the hoses? Is the vacuum hose in good condition and securely attached with no leaks?

[Stratman]

You have put the vacuum pipe on the right pipe from the petcock haven't you? The one on the side, not on the bottom?

Yes all hoses are on correctly.,but that doesn't explain the loud click

Sorry I spoke.

[tony.mon]

2500, steady slight throttle, and a click, revs die?
Sounds like a carb cough, a misfire where the carbs aren't properly balanced. But with that the engine revs normally, and runs ok.

Could be fuel, or sparks.

Vacuum is the first possibility, so it was a good question.
The symptoms you describe could well be associated with incorrect fuelling, and the fuel tap is vacuum operated. If the vacuum is not strong enough or the tap is malfunctioning then petrol will not flow into the carb float bowl, meaning that the engine won't rev properly.
One check is to pull the choke on as you try to rev it; if it revs better (not perfectly) then that's likely.
Also, try leaving it ticking over, after 5 mins or so if it hasn't died then fuel is flowing to a degree, at least.

[VTR_Stormer]

You have put the vacuum pipe on the right pipe from the petcock haven't you? The one on the side, not on the bottom?

Yes all hoses are on correctly.,but that doesn't explain the loud click

Sorry I spoke.

Mate sorry if I upset you. It was never my intent. It never sounds the same when you type it out. I have checked all the hoses and yes they are all correctly fitted. It was a good point to raise as it would be very easy to get that mixed up. Thanks for your response and I value your input.

[Stratman]

Mate sorry if I upset you. It was never my intent. It never sounds the same when you type it out. I have checked all the hoses and yes they are all correctly fitted. It was a good point to raise as it would be very easy to get that mixed up. Thanks for your response and I value your input.

No probs - was enjoying some Jura last night so perhaps a tad hasty. When these engines misfire they do produce a loud clunk, same as when they pop back through the carbs. If the diaphragm in the fuel tap is damaged this usually means that fuel flows even when there is no vacuum, but it might be worth checking in case it has disintegrated and is blocking the fuel line? If it ran after you did the CCTs then it is unlikely to be a mechanical failure IMHO but something in the fuelling.

Have you checked that the carburettors are both seating properly, as they can be a bugger to get the rubbers over the inlets and sealed properly?

[Gazfirestormowner]

I've just had this same issue after lifting carb needles turns out i never tightened in let rubbers ( school boy error )

All sorted now though

[VTR_Stormer]

Thanks again for all the input. I am caught in between fueling an mechanical only because it sounds like lack of fuel when revving but that clunck sounds very mechanical. I am a smart man and know when I have reached my limits of intelligence so off to the local bike mechanic it goes....I will let you all know what is found.....Thanks again Guys

John