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Rebuilding a 2 stroke?
- Thread starter unL33T
- Start date
boyoboy
Well-known member
yup +1 and it also determines if there are any leaks in bottom end too.
2 attempts to make a short video failed due to interruption, so forget that
Do both tests, if there is a big difference in numbers, you got issues.
I prefer cold test because that's a truer test than hot, almost any engine that runs will show better compression numbers when the metals expand with heat and make a tighter seal.
Bumping up the compression is good for racing as stated, but not for long term use.
If you run it long and hard, you're better off with a lower stress motor and make sure it isn't running too lean.
I would love to take all the credit but I can't really take any
I got a Mick Abbey tuned barrel from the UK and had it replated and Precision Cycle in Oshawa did all the machining on the head.
This is Mick's dyno run for his tune with his pipe - http://mickabbeytuning.co.uk/RS125-dyno.shtml
I had Sandy set it up for me on his dyno and with the different head and pipe it was 33.5
Of course you could take it to another dyno and it could be +/- 5hp as they all measure different.
That was with the Arrow pipe on it
Many... I don't count I just hold the starter for a few seconds until the needle stops rising. Then hold it again two more times because I don't like the number.
RonnieRev
Well-known member
that is a cylinder leak down tester, only does top end, to do the bottom end on a 2-stroke you use a pressure
tester
boyoboy
Well-known member
whoops, i didnt even look at the pic. the "pressure tester" is often called a leak down tester. the word "cylinder" in your description should have clued me in. duh.
boyoboy
Well-known member
is it as fast as it used to be, before the engine trouble started?
Seems pretty much the same. I haven't attempted to top it out yet but it'll do 115 or so just fine. Also, we did drop the compression a tad which would result in slightly reduced performance.
Because it's better for longevity and I like to take it on long highway trips.
My understanding was bitzz just used one of the cylinder gaskets that resulted in lower compression. He could answer better than I.
Well AF1 says it's reading way low but if it's running fine my gauge is probably just badly off. What are the chances both gauges are crap and read the same?
They said to just check it every time I change the spark plug. Which is a bit of a problem since I had the same plug in it since I got it... so for 7000 km, lol. I could probably still run that one but it was suggested I switch to a hotter plug.
They said to just check it every time I change the spark plug. Which is a bit of a problem since I had the same plug in it since I got it... so for 7000 km, lol. I could probably still run that one but it was suggested I switch to a hotter plug.
Normally thick head gasket to drop CR, thin gasket (or a portion of a multi-layer gasket) to increase CR. It's a pretty common practice on two-stroke sleds (and I guess bikes, but sadly I have very little experience w 2 stroke bikes). Lower CR also lets you use lower octane gas (or not have to add toluene depending on where you are starting).
I've never tried, but is their an easy way of making an adaptor to connect the gauge to an air compressor? Maybe even a rubber inflation tip would work. set the compressor at 100 psi and see what your gauge says. It should be close enough to see if it's completely broken.
Checked the tester I used against the gauge on the air supply at work. They were fairly close. The compression tester is maybe 10 PSI lower, if that. So even if I were at 100 PSI instead of 90 PSI that still isn't very good when I'm being told I should be seeing 120-140 or higher.
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