Maintenance in Eugene Oregon.. Anyone wanna help.

[Guest]

Hey guys I have lost compression in my engine.. Gone from 140 to 85-90 on both cylinders. At the direction of the forum I am going to adjust my valves and may have to do a head gasket replacement. In addition I need to vacum sync my carbs.. Anyone live in the Eugene Oregon area that wants to help me with this???? This is about all that stands between me and riding the bike

[mpencegs]

LOL.. Guess my neck of the woods is not very popular.. Finishing moving this weekend so probably gonna start on this next week or so..

[Charlie G]

I'm four hours south. If it was summer I might consider riding the bike up with the carb sync and giving you a hand. There was some guy posting lately in Salem and a few others along the way to Portland. One question, was the engine warm and was the throttle wide open? It makes a difference and I found out the hard way. Good luck.

Charlie G

8k miles on that bike? Shouldn't be that low. I'd adjust valves, rebuild carbs, sync and fire it up! Then see where your at.

[mpencegs]

The throttle was open but since the bike will not start now I was not able to warm her up.. Basically the bike was running but hung at 3500 RPM. Decided to rebuild carbs (Soaked and replaced Orings) and also replace intake boots ( Had to remove engine to remove the bolts.. Was not able to fit the tool with engine in the bike) Replaced engine and carbs and bike ran like crap.. Tried to adjust carbs and what not and no change.. Bike started bogging and then would not turn over. Checked compression and got the low readings.. I may have fouled the plugs I guess but the compression reading concerns me. Last time I took the reading and got 140 engine was cold but carbs were not on bike..

[mpencegs]

General opinion is that the valves need to be adjusted. I was hoping someone was around at least to double check me.. and drink beer LOL

[850 Combat]

Were the throttles open when testing compression? They need to be

[mpencegs]

Yeah.. Checked that.

[chef1366]

Fly me there and back on my week off.
I work one week on and one week off.

[banditom]

did you do the first reading with engine hot??

I am at a loss to determine, as to how many runs you made, between the compression readings. If the lower readings came after only a few runs, I would be looking for something besides low compression to be your problem. Especially after doing the carbs, since as I read the posts, it really didnt run right after the work. I am not real hep on zukies, but an engine thats been sitting, sometimes has gunked up rings that wont seat right until the engine has been run extensively, could this be the problem with your low pression?? Dont tear the motor apart right now until you know ALL the possible factors that could be problematic. The fact that both cyls seem very close seems to imply that wear in the rings, or a symmetrically blown head gasket,,could be the problem, if indeed you dont have a flaky gauge reading. However, ring wear takes significant time and mileage to show up. I know that when I first got my MNS, I had flaked out gauge readings, until I went thru the drill, and took into consideration every possible problem,, then when I did a hot ,,open throttle reading , got much improved, normal readings on the engine .

If I were you, I would be rechecking the gauge, to make sure there isnt something wrong with it, Ive had gauges get bits of dirt in them, and read wrong. Both vacuum and compression gauges. If it were me, I would be checking for spark, fuel, and vac leaks to be sure the basics were in place. Then once you get it running, ride to see if it has fair power, maybe compare the power to another bike with that size engine. If its similar, consider your bike to run well, if not, go thru the compression routine with your gauge again, if its off in the same fashion, put a teaspoon of oil in each spark plug hole, then retake the compression, if this raises the compression, you either have worn rings, or stuck rings. To ascertain which, ride the bike extensively, Ive read some people say,, as much as six months, to get the rings to loosen, seat and clean up and do their job. If your pression improves in that time, you had stuck rings, if not, I would be trying to borrow another compression gauge to check it again with the different gauge.

[rbond]

Here is a thought, a common mistake on twins is to put the slides in the wrong carb, thus choking it down and nearly impossible to start. Look into the carb intake throats and check for the angled cutaway, if it is flat and round, there is your problem. Rather than adjusting valves, if it is not the carbs, change the head gasket first, oh wait, take off the exhaust system and check compression. Not likely the problem, but a methodical approach will eventually zero in on the problem, my money is on a blown head gasket.