Hi all, my Firestorm refuses to rev over 5000rpm. It starts easily on the choke and ticks over OK but when it gets to 5k it just bogs down and won't pick up any more.
So far I've replaced the carbs and coils with a set from a running bike. Inlet rubbers replaced with a good used set at the same time. I've checked the fuel tap diaphragm and it looks fine, also ran the bike with a separate tank hanging from the shed roof so there would be no fuel starvation problems and the fault persists.
The battery is good (almost new) and there's a 14v charge from the reg / rec when it's running. New plugs fitted.
The timing marks on the cams on both cylinders line up when the appropriate TDC marks line up in the generator cover inspection hole.
It had some extremely noisy carbon cans on so I've put the standard ones back on with new seals, replaced the air filter and balanced the carbs.
It still won't rev. I need to ride my bike. Please can anyone help?
Won't rev over 5000 rpm
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
how long have you had the bike? did it run ok before?
if it has never run ok for you, then it sounds like cam timing is 180deg out. the timing marks will all line up, but the relationship between front and rear cyl is wrong so the airbox cant flow enough air.
if it has never run ok for you, then it sounds like cam timing is 180deg out. the timing marks will all line up, but the relationship between front and rear cyl is wrong so the airbox cant flow enough air.
AMcQ
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Roger Ditchfield
- Posts: 181
- Joined: Tue Apr 26, 2011 6:55 pm
Re: Won't rev over 5000 rpm
I agree that the most likely cause is that the rear cylinder is 180 dgs out. It is easily done unless you are familiar with the procedure as the Workshop Manual can be confusing. If you wish to email on roger@revolutionuk.co.uk I will email you back with a simplified instruction sheet. I do not know how to attach it to this Forum website!!
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
I've never had it run properly. I concentrated on doing the bearings, seals etc to get it MOT'd safe in the knowledge that the engine is solid.
I've heard of the 180 degree out timing issue but don't know how to sort it so I'll ping you a mail shortly.
I've heard of the 180 degree out timing issue but don't know how to sort it so I'll ping you a mail shortly.
Re: Won't rev over 5000 rpm
Come on someone, quick, tell Roger how to post it in the workshop section!!
Re: Won't rev over 5000 rpm
Drop it round, I'll sort it at the weekend.Thetoaddude wrote:Hi all, my Firestorm refuses to rev over 5000rpm. It starts easily on the choke and ticks over OK but when it gets to 5k it just bogs down and won't pick up any more.
So far I've replaced the carbs and coils with a set from a running bike. Inlet rubbers replaced with a good used set at the same time. I've checked the fuel tap diaphragm and it looks fine, also ran the bike with a separate tank hanging from the shed roof so there would be no fuel starvation problems and the fault persists.
The battery is good (almost new) and there's a 14v charge from the reg / rec when it's running. New plugs fitted.
The timing marks on the cams on both cylinders line up when the appropriate TDC marks line up in the generator cover inspection hole.
It had some extremely noisy carbon cans on so I've put the standard ones back on with new seals, replaced the air filter and balanced the carbs.
It still won't rev. I need to ride my bike. Please can anyone help?
Ride-in, ride-out with it fixed; an hour.
Or read the instructions already on here, then sue whoever cocked it up beforehand.
It's not falling off, it's an upgrade opportunity.
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
That's a generous offer Tony, thanks. It's just that you live flippin miles away! Roger's sent me directions to sort it out which are straight forward enough so I'll give them a crack. It's stripped down as far as the carbs / cam covers anyway.
Never say never though, I can get to Kent at 4500rpm.......
Never say never though, I can get to Kent at 4500rpm.......
Re: Won't rev over 5000 rpm
if you need a hand i am fairly local, just post on here and i will give you my mobile no
AMcQ
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
OK, I've followed Roger's instructions to , I think, the letter.
Timing mark FT lined up, the cam marks on the front cylinder line up with the cylinder head. FE at the front and FI at the rear. Cam lobes are pointing away from each other.
Turned the crank anti clock 270 degrees until RT lines up. Rear cylinder cam marks now line up with the cylinder head. RI at the front and RE at the rear, Cam lobes are pointing up and towards each other.
If I'm reading the instructions right the timing is correct and doesn't need messing with. For my peace of mind can you guys idiot-check what I've written here?
Assuming the timing is right, about the only thing I haven't tried is replacing the CDI black boxes. I know they don't often fail, but is this my next port of call?
Timing mark FT lined up, the cam marks on the front cylinder line up with the cylinder head. FE at the front and FI at the rear. Cam lobes are pointing away from each other.
Turned the crank anti clock 270 degrees until RT lines up. Rear cylinder cam marks now line up with the cylinder head. RI at the front and RE at the rear, Cam lobes are pointing up and towards each other.
If I'm reading the instructions right the timing is correct and doesn't need messing with. For my peace of mind can you guys idiot-check what I've written here?
Assuming the timing is right, about the only thing I haven't tried is replacing the CDI black boxes. I know they don't often fail, but is this my next port of call?
Re: Won't rev over 5000 rpm
You seem to have got it right, but the symptoms are exactly right for the timing being 180 degrees out. Hmmmm.
If it were my engine I'd retime the engine 180 out from where you are, to see if it then runs running properly, but I can understand if you didn't want to. No harm can occur.
All you do is set the rear (because it's easier to work on) to the "wrong" RTDC with the mark lining up but the cams pointing downwards onto the valves instead of upwards and pointing towards each other at the top.
The you remove the cct, and carefully undo each cam cap bolts one at a time to release the cam.
When you have both cams out, replace but with them in the "upwards and pointing towards each other" position.
You leave the crank where it is.
Then rebuild and go ride.
If it's no better, simply repeating the steps above get you back to where you should be.
But here's the problem:
I cannot think of a reason why this would be effective, though, even if the alternator were fitted without a key and merely located on the crank by putting it on when the engine was at the "wrong" tdc, it would affect both cylinders equally, and you shouldn't get a "180 out" situation.
I'd suggest you take up A McQ's offer; he would be able to swap over his ECU and ignition trigger boxes to rule that out. I have spares available if it turns out that was the issue, but I haven't seen symptoms like this from an ecu or ignition trigger box fault before. Is it an early or late version?
Another check:
Try revving it over 5000 for a while, then stop the engine; coast to a halt with the clutch in, and see (carefully) if both exhaust pipes are the same temp.
If one is noticeably cooler, it'll possibly be a coil or plug fault on that cylinder.
One more: have you replaced the air filter with an oiled filter- K+N or similar? An over-oiled filter or badly clogged std one could conceivably give the same symptoms.
If it were my engine I'd retime the engine 180 out from where you are, to see if it then runs running properly, but I can understand if you didn't want to. No harm can occur.
All you do is set the rear (because it's easier to work on) to the "wrong" RTDC with the mark lining up but the cams pointing downwards onto the valves instead of upwards and pointing towards each other at the top.
The you remove the cct, and carefully undo each cam cap bolts one at a time to release the cam.
When you have both cams out, replace but with them in the "upwards and pointing towards each other" position.
You leave the crank where it is.
Then rebuild and go ride.
If it's no better, simply repeating the steps above get you back to where you should be.
But here's the problem:
I cannot think of a reason why this would be effective, though, even if the alternator were fitted without a key and merely located on the crank by putting it on when the engine was at the "wrong" tdc, it would affect both cylinders equally, and you shouldn't get a "180 out" situation.
I'd suggest you take up A McQ's offer; he would be able to swap over his ECU and ignition trigger boxes to rule that out. I have spares available if it turns out that was the issue, but I haven't seen symptoms like this from an ecu or ignition trigger box fault before. Is it an early or late version?
Another check:
Try revving it over 5000 for a while, then stop the engine; coast to a halt with the clutch in, and see (carefully) if both exhaust pipes are the same temp.
If one is noticeably cooler, it'll possibly be a coil or plug fault on that cylinder.
One more: have you replaced the air filter with an oiled filter- K+N or similar? An over-oiled filter or badly clogged std one could conceivably give the same symptoms.
It's not falling off, it's an upgrade opportunity.
Re: Won't rev over 5000 rpm
Can you copy and paste Rogers detailed instruction from the email up on here please. I think you may have missed loosening the rear cam caps and lifting the cams so they don't spin while turning 270 degree's.
What you describe there is the basic timing setup only in reverse of what is in the knowlagbase timing setup as you have started from the front. That's why it's 270 degrees and not 450 degrees (1.1/4 turns) as if you went from the rear first. The problem here is that all the timing marks will line up and appear to be correct but could still be 180 out.
OK lets try this again
1) Start with the timing set for the rear with the crank at RT and rear cam lobes pointing up and inwards and lined up with RI and RE.
2) Loosen or remove the rear CCT then remove the cam caps and lift the cams off the buckets. Now holding the timing chain so it does not get caught around the crank, turn the engine at the crank 1 full turn anticlockwise until the RT is lined up once again.
(note you may want an extra pair of hands to either hold the chain or turn the crank)
3) Then put the cams back in place with the lobes pointing inwards and lined up with the RI and RE as before and refit the chain and cam caps. Tighten the CCT back up to the right amount of slack in the chain if manuals. Done, you timing will now be correct.
A couple of things here. When refitting the chain back around the cam sprockets you want to start with the Inlet cam and pull the chain taught around that first and refit loosely, then slip the chain over the Exhaust cam so all the slack in the chain is on the Tensioner side. Then tighten down the cam caps to the required torque, not one at a time though. Tighten these down in a diagonal sequence alternating between each bolt a bit at a time until you reach the required torque. Please don't over-tighten these and go easy as they have been known to snap. Personally I would go slightly under the required torque which allows for any stretch and weaknesses in the old bolts. You may want to check your valve clearances before putting the cam cover back as you have had the cams out and have re-tightend the cam caps back down. The feeler blade should slide between the cam and bucket tightly without snagging or bending but not so loose that it slides in and out without any resistance. If too tight you can loosen the cam cap bolt above it a 1/8 to 1/4 turn at a time or if too loose then tighten 1/8 to 1/4 turn (go smooth and gently) you have been warned. Bolts can and do snap. You may want to consider using new bolts and use some threadlock.
[edit]
Tony beat me to it. Oh well I have wrote down how to reset from where you are as Tony suggested.
What you describe there is the basic timing setup only in reverse of what is in the knowlagbase timing setup as you have started from the front. That's why it's 270 degrees and not 450 degrees (1.1/4 turns) as if you went from the rear first. The problem here is that all the timing marks will line up and appear to be correct but could still be 180 out.
OK lets try this again
1) Start with the timing set for the rear with the crank at RT and rear cam lobes pointing up and inwards and lined up with RI and RE.
2) Loosen or remove the rear CCT then remove the cam caps and lift the cams off the buckets. Now holding the timing chain so it does not get caught around the crank, turn the engine at the crank 1 full turn anticlockwise until the RT is lined up once again.
(note you may want an extra pair of hands to either hold the chain or turn the crank)
3) Then put the cams back in place with the lobes pointing inwards and lined up with the RI and RE as before and refit the chain and cam caps. Tighten the CCT back up to the right amount of slack in the chain if manuals. Done, you timing will now be correct.
A couple of things here. When refitting the chain back around the cam sprockets you want to start with the Inlet cam and pull the chain taught around that first and refit loosely, then slip the chain over the Exhaust cam so all the slack in the chain is on the Tensioner side. Then tighten down the cam caps to the required torque, not one at a time though. Tighten these down in a diagonal sequence alternating between each bolt a bit at a time until you reach the required torque. Please don't over-tighten these and go easy as they have been known to snap. Personally I would go slightly under the required torque which allows for any stretch and weaknesses in the old bolts. You may want to check your valve clearances before putting the cam cover back as you have had the cams out and have re-tightend the cam caps back down. The feeler blade should slide between the cam and bucket tightly without snagging or bending but not so loose that it slides in and out without any resistance. If too tight you can loosen the cam cap bolt above it a 1/8 to 1/4 turn at a time or if too loose then tighten 1/8 to 1/4 turn (go smooth and gently) you have been warned. Bolts can and do snap. You may want to consider using new bolts and use some threadlock.
[edit]
Tony beat me to it. Oh well I have wrote down how to reset from where you are as Tony suggested.
==============================Enter the Darkside
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
Thanks for all the advice and apologies for being a pain in the elbow, but this is driving me crackers.
I've checked the timing once more and I'm happy that it's actually correct. Perhaps silly, but I've been checking the running with no airbox or filter on so I could access the carbs and check for air leaks. I've put everything back together with new HiFlo filter and I now have full revs available in neutral.
On a test ride the fault is still there under load. It will just about pull through 5000 but miss fires like mad. Fuel tap is fine so I'm thinking it has to be the spark failing under load?
However, when I refitted the standard cans I put new gaskets in each side, but didn't replace the centre gasket. Now it's not masked by the racket from the carbon cans I can hear a kind of ticking noise that sounds like tappets but is coming from the back of the engine, not from the top end - possibly a blow through a dodgy gasket. Is that enough to cause serious running problems? I've ordered up a new gasket today but I still don't know which particular tree I ought to be barking up.
I've checked the timing once more and I'm happy that it's actually correct. Perhaps silly, but I've been checking the running with no airbox or filter on so I could access the carbs and check for air leaks. I've put everything back together with new HiFlo filter and I now have full revs available in neutral.
On a test ride the fault is still there under load. It will just about pull through 5000 but miss fires like mad. Fuel tap is fine so I'm thinking it has to be the spark failing under load?
However, when I refitted the standard cans I put new gaskets in each side, but didn't replace the centre gasket. Now it's not masked by the racket from the carbon cans I can hear a kind of ticking noise that sounds like tappets but is coming from the back of the engine, not from the top end - possibly a blow through a dodgy gasket. Is that enough to cause serious running problems? I've ordered up a new gasket today but I still don't know which particular tree I ought to be barking up.
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lloydie
- Posts: 20923
- Joined: Mon Jan 17, 2011 11:16 pm
- Location: In the garage somewhere in Coventry
Re: Won't rev over 5000 rpm
Have you replaced the vac line from the front cylinder to the fuel rock ?
Have you removed the fuel lines from the tank with the tap turned on ?
Did fuel come out ?
They will still Rev out with blown connector seals .
Have you removed the fuel lines from the tank with the tap turned on ?
Did fuel come out ?
They will still Rev out with blown connector seals .
Re: Won't rev over 5000 rpm
I had a similar rev problem a while back whilst playing with the jetting & needle height.
It would rev ok in idle & would get me to the carriage way with no issues because it was under the 5000rpm.
On the carriage way though, no go beyond the 5000rpm mark. I'd Rev it with the clutch in & slip the clutch to try & trick the bike to go beyond the issue. Nothing worked.
Like you I was very concerned, it turned out to be a cv diaphragm which was not seating properly
Now I always use super sticky silicon "valve" grease to stick the cv diaphragm in place & have had no issues since
It would rev ok in idle & would get me to the carriage way with no issues because it was under the 5000rpm.
On the carriage way though, no go beyond the 5000rpm mark. I'd Rev it with the clutch in & slip the clutch to try & trick the bike to go beyond the issue. Nothing worked.
Like you I was very concerned, it turned out to be a cv diaphragm which was not seating properly
Now I always use super sticky silicon "valve" grease to stick the cv diaphragm in place & have had no issues since
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Thetoaddude
- Posts: 21
- Joined: Mon May 16, 2016 8:10 am
- Location: Walsall
Re: Won't rev over 5000 rpm
The fuel tap vacuum hose and diaphragms check out OK.
It's on it's second set of carbs and has the same symptoms and I'd hope not to have the same fault on both sets of carbs, but you never know so I guess it's carbs off again to check out the diaphragms. Oh joy!
Thanks lads.
It's on it's second set of carbs and has the same symptoms and I'd hope not to have the same fault on both sets of carbs, but you never know so I guess it's carbs off again to check out the diaphragms. Oh joy!
Thanks lads.