Tight valve clearances.

Anyone on here had exp with tight valves?

I checked the rear cylinder on mine after chasing a problem with rough running low in the RPM range and I suspect a loss of power higher up. I have found that the rear intakes are 0.002mm under minimum spec, might not sound like much but I think it could be enough to make the engine unballanced.

I aint checked the front since it'll need doing and I dont feel confident with taking cam's out myself tbh

So im wondering anyone on here had valve clearances cause your bike to run like a bit of a dog?

Cheeeeeers

That shouldnt cause an issue, did you check hot or cold?

If you have rough running at idle when hot i would recheck them red hot and see if there any clearance at all if you still thinks it might be that. Or easier would be put vac guages on and check balance cus if the valves are slightly open there would be low vacumn

I dont think its a problem of the valve not closing right, I think its more a problem of it being open a little too long, or at least for a different amount of time compaired to the other cylinder, so one is getting more charge than the other...

It was done cold (very cold I might add Grrr) Vac's are pretty uniform...

The issue, not mentioned it have I... at around 3000rpm on constant throttle (i.e. cruising) or just closing the throttle the bike just feels like one cylinder is working and the other is just trying to slow it down. Makes it a bitch to ride in town... I've checked for vacuum leaks with none present, currently running fuel cleaning stuff but Im pretty sure all that is hunky dorie... new spark plugs that look the right colour, new HT leads... Not much left but the Valves.

What little i've got out of some people on other sites and google point towards it causing a potential problem.

The SV generally goes tighter on the rear cylinder. The majority of the race SV650's that we look after need the rears doing when they come in.

Generally dont get many running rough on it though.

im almost certain its not valve clearances more like play in throttle linkage or poor carb balancing (assuming its not injected lol)

just sounds like one has more throttle than other

SV racer, To be honest when its reving 4K rpm + you cant really tell, so i guess if the racers do have a similar issue they wouldnt tell as id guess they rarely cruise at 3k round a track... so they might not feel it, cheers for input though

Originally Posted by Rai86

im almost certain its not valve clearances more like play in throttle linkage or poor carb balancing (assuming its not injected lol)

just sounds like one has more throttle than other

Its a solid linkage and its FI...



Suppose I should see about getting some TB's off of Ebay just incase its something I cant physically see to fix. I think ill get the valve clearances sorted anyway, as its just a good idea.

You could be right about it not being ballanced though if a injector is blocked...

Vacuum at stand still seems ballanced from tickover upto higher RPM's. Sigh.

Get a dyno run so you can see what mixtures are like under load, should be able to see easily whats going on then, still think you would wasting money getting tappets done at the mo

it may be runnning a bit lean a power commander may be able to fix it

Indeed, ill have to see what the insurance think to using the PC3... I can play around with a few settings in the ECU to richen up the system so ill see. Even if it mucks the rest of the throttle fueling up at least ill know.

Money fortunatly isnt so much an issue. I just want to know whats brought this on, so I can sort it.

Drag this out of the ditch a little...

When the engine is cool it runs pretty much bang on! Once its upto temp it starts coughing and spluttering and well feels crap at less than 3500rpm. This to me kinda points again at the valves. Though I guess ill only know once I finally get them sorted.

its defo running lean if its fine when its cold, cus the system auotmatically richens the mixture on cold start