Hi all tech heads,

I just did a compression test on the softie and came up with 160psi.

This was a cold test and after reading the manual I found you are supposed to test with the engine hot.

Anyhow the bike has 58,000kls on the clock.  the first compression stroke raised the needle to around 100psi then quickly climbed to 160psi front and 157psi rear.

Can anyone tell me if this is a good enough indication all is all right? or should I redo the test hot.

Thank in advance,

Bluey

Id be happy with that

Thanks for the response Oz and Ando. I'll have another go when hot.

I have SE204 cams with stock heads, pistons gasket etc. I don't think these cams would make much difference to compression as intake closes early.

Thanks again,

Bluey

Bluey,

My digital Workshop Service Manual (09FXST TC 96B) quotes "final readings are not to be less than 125PSI and variance between cylinders no more than 10%" unquote, also as you are already aware off test to be done on engine at normal operating temp.

Quite obviously the 160 psi is good but the variance between cylinders is the other check you need to keep an eye on. If you are using a Bourdon tube type gauge, it is not uncommon for these to be knocked around in the bottom of tool boxes and therefore may read low, however a reading on the low side compared against the ideal pressure ie 160 compared to 180, does not necessarily mean cylinder issues, but if the same gauge reads greater than 10% across both cylinders then investigation may be warranted.

Cheers Paul

Paul

Built a mates 96ci with andrews 54h cams and heads decked to 79cc and it was 185psi in both pots
it was a nice cheap combo and it went hard

hi,   comp test hot & the throttle fully open count the compt stroke's  1-2-then 3  she should push max between 3 to 4  comp  stroke's,   watch the gauge  needle ,  screw in type are the best

Hi Blokes, thanks for your coments.

Bad I was thinking like you and didn't bother with another test, I realized my problem was with tuning on the 2:2's.

My compression tester is the screw in type.

I re installed the 2:1 RB Racing pipe and the map I had tuned for it and all is well again. I just cut the worn tail piece off and welded a modified HD touring turn out muffler on, minus the baffle of course. The weld is behind the chrome collector heat shield.

I was going to get the 2:1 tail pipe rechromed but it's possibly cheaper to buy a new pipe in the future. I might even get it powder coated black, dunno.

Thanks again blokes your coments are much appreciated.

Bluey 

 

Good look and I bet it performs well

If it's looks your after you wouldn't buy an RB Racing pipe, saying that if you are after performance you cannot go past them.

Here is a link to RBR's web site, lots of good info on exhaust design.

http://www.rbracing-rsr.com/exhausttech.htm

They design pipes for performance and do a great job. We have quite a few different 2:1 pipes on various HD's and I get lots of comments mine sound good. They definitely smooth out the ride and produce more low and mid power.

On a recent trip to Cooktown I got a respectable 21.5 kls to the litre riding in a group (third from front, that makes a difference). I calculated it over three consecutive fill-ups. It doesn't run hot and gets good mileage if you don't twist it.

When I had the Thundermax Autotune I never got over 20 kls. to the litre but had great power. I only put the TTS MT on to try but ended up leaving it on, it's not a bad system.

I have had a play tuning with SEPST, TTS and Thundermax, I personally prefer the Thundermax to the others but like the others it has it's short comings in different ways.