Gpz 1100 B2 one tooth out ?

[Richard L]

Hello , Guten Tag as they say here !
I have recently collected my B2 from a dealer who has been doing some work on the head ( ie cams out ) amongst other things. The bike runs 34mm
Mikuni cv carbs Dynojet stage 3 and K and N s and since its return I have noticed it '' running on '' ( feels like the choke is on ) with a closed throttle.
Because the dealer had played around with my carb settings ( presumably to overcome this problem ) I returned them to their previous settings and then experimented with needle position etc all to no avail.
Following advice from my brother ( Pluto ) I have checked the valve timing which in my inexperienced eyes appears to be 1 tooth out. The dealer swears blind that it is not incorrect ( I sent him the same pics ) but caused by wear in the cam chain , guides and cam sprockets. I do not believe him , what do you think ?




Thanks in advance for any assistance
Richard

[PAULJAC47]

Richard i would agree, inlet and exhaust cams pointers should be level with head at T reckon he is spinning you a yarn about the wear etc....Paul J

https://www.google.co.uk/search?q=gpz+1 ... B464%3B640

[Jumbo]

It is hard to see in the pictures but it would be worth counting the chain as in the drawing link posted by Paul J.

[zed1015]

That does look correct from that angle..
You just need to have the front (exhaust) cam mark to line up at TDC and check you have the correct amount of cam chain pins counted back to the dot on the inlet.

[Compo1955]

Exhaust cam looks to be one tooth retarded. If you remove the timing chain tensioner to let the chain go slack, you might be able to advance the cam by one tooth without removing the camshaft, IF there is enough clearance between the head and cam sprocket...

[zed1015]

Exhaust cam looks to be one tooth retarded. If you remove the timing chain tensioner to let the chain go slack, you might be able to advance the cam by one tooth without removing the camshaft, IF there is enough clearance between the head and cam sprocket...

+1.
I didn't see that second pic first time round.
Definitely one tooth off on the exhaust and if the pin count is correct to the inlet then it's probably jumped a tooth on the crank and both cams are retarded.

[Al]

The inlet cam is correct as it is leave it like that. When you button down the cam cover it advances the inlet cam ONLY and will bring the arrow to level with the top head mating surface.

Stretch in the cam chain and wear in the front slipper blade would easily account for that innacuracy with the exhaust cam but that is not the point. The cam needs to be rotated to take account of that wear and that is what should have happened.
You cannot 'roll' the chain over the sprocket or the sprocket within the chain without lifting the cam slightly because there is not enough slack in the chain to do this. Though there is just enough room for the links to pass the tunnel at the front.
It can however move of its own accord and will do so at any available opportunity.
Normally when you shut the throttle and down shift, enough slack will do this for you or when re-placing the cam cover after top end work such as here.
Non- manipulation of the auto-tensioner is the culprit in both cases.
The chain cannot jump a tooth at the crank. There is a bolt in the centre cap which prevents it.
It is very likely that he set it correctly and either he or you will have caused it to jump one tooth on the exhaust. Him replacing the cover or you taking it off.
It will run perfectly well with one tooth out without any mechanical issues.
That said it will be different!
Different lobe centre values calculated from actual valve timing will give you torque and HP in different places than before.
The problem comes when you couple this with CV carbs as they are very sensitive to changes in vacuum.
Changes in valve timing causes radical changes in inlet manifold vacuum particularly at idle and up to 1/4 throttle. This will send you off looking to richen or weaken the mixture to compensate.

I would look for air leaks first if its 'running on' and if it has that heavy rhythmic idle that feels like 'choke' maybe look to weaken it a little.
The latter will be accompanied by a very noticeable increase in low end torque.
If you re-set the exhaust arrow to be horizontal i would return to standard settings.
Are the carb rubbers glued to the head?

AL

[z1bman]

the cut outs in the end of the cams should be half way between the cylinder head mating surface when the valve timing is correct

[pluto]

The pin count is correct at 44, my theory is he got the exhaust cam position wrong initially and then set the inlet cam correctly (as in 44 pin count) but that then means both cams are out by 1 tooth which would screw it up somewhat.
Both cams need to advance 1 tooth surely?

[PAULJAC47]

Found this?????

as can be seen the timing marks all line up well which tells us that the cam chain is not worn (note: timing chains do not stretch, they wear thus getting longer and making one or both of the exhaust or intake marks not line up correctly. If when crankshaft is on TDC (top dead centre) you find that the corresponding cam timing marks do not line up or are slightly clockwise of their intended position then the time chain is therefore worn).

[Richard L]

Hi and thanks for all your comments and observations, Before the bike went in it ran really well and had none of these problems,the cam chain and guides have done less than 1500 miles, the inlet rubbers are new and glued to the head and the carbs are supported to take the weight off the rubbers , the running on had started before I took the cam cover off so I am still sure it is something he has done , I have to work out what to do next .
Experts such as yourselves would probably just whip the cams out change the position and see what difference it makes but I have little experience , and no workshop or garage which is why I paid good money for somone else to do it for me.
Thanks
Richard

[Al]

Just my judgement but it did not look as if the inlet was nearly a full pin retarded as the exhaust looks to be at least one pin that direction but agree 44 pin count is correct.

Richard part of my post above is missing.

P.S. Inverted tooth sprockets and HYVO chains look worn out even when new. You can see daylight between them. Dont be having any of it

[z1bman]

[zed1015]

The pin count is correct at 44, my theory is he got the exhaust cam position wrong initially and then set the inlet cam correctly (as in 44 pin count) but that then means both cams are out by 1 tooth which would screw it up somewhat.
Both cams need to advance 1 tooth surely?

Yes! Both cams a tooth out and need to be advanced.

[pluto]

A quick report on the outcome of this, went to Germany on the way to Spa and had a proper look. The dealer had indeed got it all wrong and set both exhaust and inlet cams 1 tooth out. We moved the cams to the correct position readjusted the carbs and the bike is now running sweet as a nut. A good result.