Low Compression Issue

[PMKXS11]

I finally got my wiring far enough along to turn the bike over, so I decided to do a compression check and was not pleased with the results. Cylinders 1 and 4 are both reading 145 psi and 2 and 3 aren't even getting up to 50 psi. Is is safe to assume the head gasket is the culprit or am I missing something here?

Here are the engine specs
Bored to 1196 with Wiseco piston kit.
Mild headwork done + 3 angle valve job
Web Cam 110 grind cams (.395/.395) + valve spring kit
Crower connecting rods

[jetmechmarty]

Have you checked the valve clearance?

[PMKXS11]

Valve clearances were done at the machine shop that did all the head work. I can pull the valve cover and take a look myself. They asked for the specs when they assembled the head and shimmed the buckets accordingly.

[TopCatGr58]

Your engine specs seem to indicate that you know what you're doing so I'm sure you had the throttle wide open, or the carbs were OFF.

Is this engine even broken in, or is it a fresh rebuild....sounds like a fresh build. I would think that it should produce decent compression, like #'s 1-4 but perhaps not until it's truly broken in and the rings are fully seated??

Compression rings installed right side up or not???

I didn't review what year before I posted, but remember another Xsive that tried to use the RUBBER cam well liner/gasket with a new headgasket, that seal/liner was eliminated with the later design/gaskets, if used will be too thick in the middle??

T.C.

[BA80]

Possible the head gasket is blown between those 2 cylinders. One easy way to check is put the plug back into the one you don't have the guage on.

Try it both ways. If the gasket is the issue the compression will go up in 1 or both.

If it has run that way for a length of time there might be a tunnel burnt between them in the jugs, head, or both.

[PMKXS11]

Your engine specs seem to indicate that you know what you're doing so I'm sure you had the throttle wide open, or the carbs were OFF.

I didn't review what year before I posted, but remember another Xsive that tried to use the RUBBER cam well liner/gasket with a new headgasket, that seal/liner was eliminated with the later design/gaskets, if used will be too thick in the middle??

T.C.

I had the throttle open during the tests.
Now that you mention it, the front nut on the cylinder right above the CCT has some oil coming from the gasket. I bet it is that rubber cam well liner as you call it. Damn, I don't wanna pull my head off again

[PMKXS11]

Success! Pulled that stupid rubber gasket and bolted it back together and am getting 150 psi across the board. Thanks for the input!

[TopCatGr58]

Success! Pulled that stupid rubber gasket and bolted it back together and am getting 150 psi across the board. Thanks for the input!

Phew, Glad that was it, I was worried about insulting you/your intelligence/experience with wrenching! Yeah, that liner has fooled a few folks! Congrats that you got it right and didn't damage the head!

T.C.

[PMKXS11]

Phew, Glad that was it, I was worried about insulting you/your intelligence/experience with wrenching! Yeah, that liner has fooled a few folks! Congrats that you got it right and didn't damage the head!

T.C.

Haha thanks, I wouldn't be offended if you did, these machines have thrown me some curve balls I would have never figured out without the help of this site.

[PMKXS11]

Unfortunately I still have a leak above the CCT, so I think that head gasket might have gotten damaged from that rubber piece. Time to pull the head again

[TopCatGr58]

Hey again,

I'm not a PRO mech, so I don't know for sure if you could use any sealant on the portion that prevents oil leaks? I do know you can't use it on the metal fire ring section. When I did my Wiseco it came with a COMETIC brand type head gasket. A quick search on Ebay showed this one for the XS11 in the 1196cc variety:

http://www.ebay.com/itm/79-81-YAMAHA...item20d952c8d6

That one is from Japan, ~$31.00 but $12.00 S&H.

Here's the COMETIC one:

http://www.shopengineparts.com/produ...+()&type=model

I tried to go thru part of the checkout, it shows ~$54.00 but didn't show it was going to charge for shipping or tax!?

Anyways, hopefully someone with more experience/knowledge about using/repairing headgaskets will chime in....are you watching TOD/TRBIG or Greg!?

The Cometic I had seemed like a GRAPHITE or Asbestos type vs. the hard fiber type, but that was some 14 years ago.....not sure what it's made of now, and the second link/COMETIC didn't show a photo!?

T.C.

[bikerphil]

TC, maybe there should be a warning posted somewhere about that cam chain tunnel gasket that has been omitted, JAT

[PMKXS11]

On monday, I'm going to call Wiseco direct and ask if they have extra gaskets to purchase. For the time being, I'll try some hi temp RTV on that spot. Can the cylinder head be completely removed in the frame? All I did was slide it up, had a friend hold it, and I cut the rubber one in half and pulled it out carefully

[MaximPhil]

On monday, I'm going to call Wiseco direct and ask if they have extra gaskets to purchase. For the time being, I'll try some hi temp RTV on that spot. Can the cylinder head be completely removed in the frame? All I did was slide it up, had a friend hold it, and I cut the rubber one in half and pulled it out carefully

Hi PMK,
Yes the head can be removed with the engine in the frame. Like much of the real work on my bike...I have seen it done
If I recall the cam cover has to come off and it is a tight fit. I do not recall if the cams were taken off before or after removal. Secure the cam chain after splitting or it will drop down the tube and that is not good even if you are going to replace the chain it needs to stay in place.
Of course You do have a manual
Phil

[PMKXS11]

Hi PMK,
Yes the head can be removed with the engine in the frame. Like much of the real work on my bike...I have seen it done
If I recall the cam cover has to come off and it is a tight fit. I do not recall if the cams were taken off before or after removal. Secure the cam chain after splitting or it will drop down the tube and that is not good even if you are going to replace the chain it needs to stay in place.
Of course You do have a manual
Phil

Awesome, I'll try my luck with the RTV and if need be I'll pull her apart to swap head gaskets. I rebuilt this engine on the bench so it was a lot easier.