Tight valve clearances.

[ThEGr33k]

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

[Rai86]

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

[ThEGr33k]

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.

[SV650Racer]

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.

[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

[ThEGr33k]

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 :)

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...

http://i698.photobucket.com/albums/vv347/rossieau/IMG_1610.jpg

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.

[Rai86]

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

[ThEGr33k]

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. :(

[ThEGr33k]

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.

[Rai86]

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

[ThEGr33k]

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


I mean cool asin first 15 mins of running, before things "really" warm up. There is something else though that I could check that I didn't think about, the coolant temp sensor, I dont think that the dash temp and ECU measured temp are the same sensor! heh. Something else to check I guess. But if it is that then in theory it would be running rich... which could be right, I have very little engine breaking atm! Which is strange on a big twin! :rolleyes:

Cheers for the input Rai, making me think more. I got to be honest though I hope to hell that it is the damn valves, then it'll be the end of it :rolleyes:

Oh and found this (http://autorepair.about.com/library/a/1i/bl289i.htm), kinda supports my theory a little.

[Berlin]

Hi Nick.
I don't think its your valves.

Tight valves cause loss of compression. If it's on the inlet side, you get a "pop" going back up the inlet trackt when the engine is trying to start or is running at tickover. on the exhaust side of things it can create backfires. But basically it casues low compression which can manifest itself as a bike that's difficult to start or lacks power. 0.002mm out is nothing to worry about unless its getting tighter.

As your bike is an FI, I'd start by checking all sensors on the bike to see if they are working. Go through every connector and sensor and confirm its doing what it should be. Then I'd move in to the injectors to see if something wasn't stuck in there. After that I'd look at the electrics.

A dyno run will tell you if there's something up but for the same money they could reset your FI for you at a garage. Have you added any bolt on goodies (pipes, filters etc) that could have altered the fuelling? Standard road fuelling for bikes is deliberately weakened at the lover end of the modrange for emissions testinga nd it should come as standard advise that if you buy a new FI road bike you have it reprogrammed to fuel properly instead of trying to meed emission targets.

A second hand PC111 on ebay will set you back as little as 50 quid and you can install your own maps based on downloadable maps to suit any extras you may have on the bike. orf alternatively set it up for standard.

C

[Spanner Man]

Good morning all.


When attempting to find a poor running issue, a very old rule of thumb is to make sure everything else is in order, & that includes valve clearances.
If you have already measured clearances that are under specification on the rear cylinder, you had better get them corrected, & the front cylinder checked & adjusted if necessary. Only then should you start to look elsewhere, for you could end up chasing your tail, metaphorically speaking.

Because a certain type of engine will exhibit a certain characteristic, such as SV rear cylinder clearances getting tight while the fronts are ok. It's not good practise to assume that they're all going to be like it. I've serviced many SV's from new, & seen many cases where the rears were fine & the fronts needed doing at the first shim service.


Cheers.

[ThEGr33k]

Hi Nick.
I don't think its your valves.

Tight valves cause loss of compression. If it's on the inlet side, you get a "pop" going back up the inlet trackt when the engine is trying to start or is running at tickover. on the exhaust side of things it can create backfires. But basically it casues low compression which can manifest itself as a bike that's difficult to start or lacks power. 0.002mm out is nothing to worry about unless its getting tighter.

As your bike is an FI, I'd start by checking all sensors on the bike to see if they are working. Go through every connector and sensor and confirm its doing what it should be. Then I'd move in to the injectors to see if something wasn't stuck in there. After that I'd look at the electrics.

A dyno run will tell you if there's something up but for the same money they could reset your FI for you at a garage. Have you added any bolt on goodies (pipes, filters etc) that could have altered the fuelling? Standard road fuelling for bikes is deliberately weakened at the lover end of the modrange for emissions testinga nd it should come as standard advise that if you buy a new FI road bike you have it reprogrammed to fuel properly instead of trying to meed emission targets.

A second hand PC111 on ebay will set you back as little as 50 quid and you can install your own maps based on downloadable maps to suit any extras you may have on the bike. orf alternatively set it up for standard.

C

Thanks for the reply. My FI is running an aftermarket map made by one of the Aprilia forum guys, has been running brilliant with that for 18K miles, so im fairly happy that isnt the issue. Nothing to reset on these ECU's they are pretty good in that its all unhouse, any codes that might be shown are stored and can be put up with no effort (great init).

Its funny you should mention that popping into the airbox, I do get that, off of the rear cylinder! It happened last just after I checked the valve clearances.

The rear intake clearances are tight, as you mention by 0.002mm. The exhaust, one is right on the minimim and one is 0.002mm above, so all the clearances are on or below the lower end of the scale.

I have checked many things and even replaces a few (because I had the parts anyway) including the Manifold pressure sensor and TPS. Also checked intake temp which appears to be working. There arnt really any others that effect the mapping on these bikes. They are open Cct...

I have a few goodies on, End cans but im running the bungs in them so they arnt flowing at their best, I also have a pipercross filter and enlarged intake boot, I was running a larger airbox as well but im not atm and tbh it dont seem to have made much odds. It has been running perfectly with all these mods before now so im fairly confident it isnt those.

I do have a PC3, but there are two things. I need to know that it is simply fueling or ive wasted money if it is something else because the only way to go with this custom eprom is for a custom map... Also insurance, need to find out if they mind. ha ha

Cheers for the input Berlin :)

Good morning all.


When attempting to find a poor running issue, a very old rule of thumb is to make sure everything else is in order, & that includes valve clearances.
If you have already measured clearances that are under specification on the rear cylinder, you had better get them corrected, & the front cylinder checked & adjusted if necessary. Only then should you start to look elsewhere, for you could end up chasing your tail, metaphorically speaking.

Because a certain type of engine will exhibit a certain characteristic, such as SV rear cylinder clearances getting tight while the fronts are ok. It's not good practise assume that they're all going to be like it. I've serviced many SV's from new, & seen many cases where the rears were fine & the fronts needed doing at the first shim service.


Cheers.

Im goin to be taking it into a shop for the valves adjusting, will be trying to get it in next week. Since im goin to be getting the shop to do it I figured there wasnt much need to check the front since they will. Ill tell them that I know some are too tight so that they know im happy to check them! Should make sure that they do sort them and not pretend. :rolleyes:

I have also been running some fuel cleaner (BG44K highly recommended apparently) for the last 30 miles, so if that is an issue then this stuff should sort that out...

Cheers for the input, with what you said it sounds like im going about this in the right way. :)

[ThEGr33k]

Just phoned the bike shop that is sorting the Valve check and indeed they are replacing the rear intake shims as they are on the tight side. Should (provided the delivery arrives) be done soon so I can see how it is after those are put back in spec.

Fingures crossed it will be back to being brilliant :D

[SV650Racer]

Just phoned the bike shop that is sorting the Valve check and indeed they are replacing the rear intake shims as they are on the tight side. Should (provided the delivery arrives) be done soon so I can see how it is after those are put back in spec.

Fingures crossed it will be back to being brilliant :D

Good news then.:cool:.

[ThEGr33k]

Good news then.:cool:.


It is, especially if it does fix the slight stumble "thing" I been experiencing. :rolleyes: Cross your fingers for me :)

[Luckypants]

Just for interest Nick who is doing the valve check for you?

[ThEGr33k]

Just for interest Nick who is doing the valve check for you?

Independent mechanic shop (not a dealer, don't sell bikes I don't think), called RTT in Hoyland common, Barnlsey.

Why you ask?

http://www.roadtrackandtrial.co.uk/Contact-Us-2-w.asp

Didnt know they had a site! ha ha.