Subject: GRiSO 1100 Compression. Mon Jan 02, 2023 4:39 pm
Today I did a valve clearance check on the bike. We've done 183k now. I have not done one before, but thought this time, we will do a compression test, since I had recently got a compression tester.
Pulling the spark plugs out, the right side was clean, the left sde a little discolored. Maybe some oil getting in from somewhere? The test was done on a cold engine. Checking the compression. The left side (side stand side) is approx. 95psi. (mmmm that's a tad low) The right side being 135psi.
Hard to ignore that something needs doing. The right side I would consider to be good for the age and km's. the left side, given the sparkplug, could be rings. either worn, or cracked, or maybe a valve. See the pictures below and any thoughts comments and all that stuff most welcome and appreciated.
Pete, his first words were: Today I did a valve clearance check on the bike.
While I agree with what's suggested above, I'll suggest that when you do your leak down, while blowing air into the cylinder, slowly turn over the motor. If there's a bit of debris holding a valve open a bit, you might get lucky and blow it out. Slim chance, but still a chance.
You did have the throttle fully open when you did the test yes?
When we're the valves last checked? While the suggested 10K km is very conservative if it's run for any time with a tight valve it may well of burnt it.
Good point, I should have recalled that fact when I did the car check. The valves were checked less than 10k ago, they were fine at that time, and only minor adjustment on the right side inlet this time.
I did a retest of both side a short moment ago, throttle wide, and the right side was as up a similar improvement as the left. 5psi approx , the left, a little improvement up to 100psi. [You must be registered and logged in to see this image.]
I'll have to look at what I need to do a leak down test. Thanks for the information.
It's a bit tired on that side especially. Do a leak down test but I'd lay money on a leaky valve at this age.
At 183K km it's overdue for a cam chain anyway so I'd look at doing that and freshening up the heads. While the rings may be tired as well they are likely to be less of an issue than the valves. That's not to say it won't be rings at that mileage, (The leak down test will tell you.) but my spidey sense says the most likely culprit will be a valve. Probably exhaust.
Mine did this at around 140,000 km. Measured new rings and compared them to the old ones - exactly the same! I fitted these anyway. Real problem was the valve seats were all pitted - a valve job and away we went...
Once I know what the leak test tells me, I'll decide the direction of service is. I'm gonna guess part/s sourcing could be easy/dramatically hard and time consuming. , could be in need of valves, rings, timing chain, any other parts worth doing same time? But a good excuse to put a video together of my progress. The timing chain.... That would require taking the engine out of the frame I imagine? I'll read the manual. I'll let ya'll know the result of the leak test.
Nah, you can do the timing chain in the frame. I'd also install a Valtek blade type cam chain tensioner but make sure you specify it's for a GRiSO/CARC bike as they re-designed it for these models as the earlier type didn't fit. Valves are easy enough, they are the same as the V11 series I believe but I can check that for you. As for rings? They went NLA a while back but I'm sure someone has worked out a replacement by now. I think I may have a set floating about though.
If the guides are worn get them K-lined rather than replacing them if they aren't loose in the head.
I can order this stuff for you if you want? What year is your bike?
GhostBullet likes this post
Posts : 239 Join date : 2015-06-02
Subject: Re: GRiSO 1100 Compression. Thu Jan 12, 2023 10:49 am
Howdy folks, Here's a wee video of where we are at the mo with the mighty GRiSO