To much compresion,any ideas why?

[YTZ250#1]

A friend of mine has an 84 big red.He had a bore job done and installed a new piston and rings,also a new cam.It starts and runs,but is pushing
270# of compresion.His book says it should be around 165.2 gages had the same reading so that rules out a bad one.he is affraid that if he runs it to much that it will blow appart.Any ideas what could cause this thing to be so high on compresion?

[250R4Ever]

your friend must be reading the wrong number or something because if it had 270lbs of compression you wouldn't be able to start it with the pull rope. i know a mechanic around here that has a 85 tecate 3 and his had 201lbs of compression at the plug and he has broken kick starters left and right, so you must be reading the numbers wrong or you're not testing it right or something.

[KASEY]

i run 225 psi in my 250r and thats alot!!! so something is really wrong!!!! either your guage is wrong ,, i don't think even arnold could pull start that!!!!! better check it again,,,,

[TRI-Zbrian]

lol OMG that thing would rip your arm off trying to pull start it :twisted:

[250R4Ever]

i run 225 psi in my 250r and thats alot!!! so something is really wrong!!!! either your guage is wrong ,, i don't think even arnold could pull start that!!!!! better check it again,,,,

or arnold would be picking up the whole trike by the pull rope while trying to start it. lol

[YTZ250#1]

It has electric start so I don't think he is pulling it.And he has had 2 gages on it,they both read 270#.he is very mechanicly inclined and is reading the gage right.Any other Ideas?

[slippy4]

with that much compression i dont think regular pump gas would run right in it. is it warm when he tests it?

[250R4Ever]

i don't think an atv starter can turn over that much compression

[mudduck14843]

did he put in a high dome piston?
my 200x pegged a 200psi meter but i have a high comp piston.
i would run airplane fuel or race fuel in it and run her.

[ATCMedic]

You mention it just had a bore job done, did the machine shop deck the cylinder or mill the head? That would raise the compression ratio...

[Dan Tenn]

Are you doing the compresion test with the throttle wide open, and pulling it over a few times ?

[YTZ250#1]

Here is what we found out.It is bored .80 because the shop messed up the first time and had to rebore it.They also ordered the piston as the replacement for the one that got messed up in the bad bore.They ordered
a 12.1 piston,and it is supposed to be 7or8.1.Any body know where we can find a low comp piston?All the books I have only list the 12.1.

[TRI-Zbrian]

try dennis kirk

www.denniskirk.com

[rob0781]

did he put in a high dome piston?
my 200x pegged a 200psi meter but i have a high comp piston.
i would run airplane fuel or race fuel in it and run her.




1984 big red almost mint STOLEN BY: EJ'S TOWING AND REPAIR IN HORNELL, NEW YORK(LEGALLY)!!!





How do you legally steal a trike???

[mudduck14843]

[quote="




How do you legally steal a trike???



it was towed and he wouldn't let me have it back for a couple weeks then when he finally released it the storage/tow bill was outragous

[hondatrikesrule22]

270.... :shock: You would have blood blisters the size of quarters from the pull rope jerking out of your hand lol.I can't stand starting my 110 because it jerks out of my hand. :rolleyes:

[YTZ250#1]

E-LEC-TRIC-STAR-T. It starts right up,but he is affraid of doing damage to the lower end.With that much compresion the rod will be the first thing to go.

[short4stuff]

possibly could the timing be out enough that it has that much compression, but still runs??? idk.

[mudduck14843]

compression is a GOOD thing, i always thought!!!

[eh_tee_see]

is this a 200es or a 250??? cause the 250's are a kickstart not a pull start...

[Grant2k]

gee i wish too much compression was the problem with my 200s!

[YTZ250#1]

It is a 200es big red,And the 250es big red also has electric start with a pull start back up,Not kick.I beleave the only 250 hondas with kick start are the 250x and the 250r.correct me if I'm wrong.

[broook]

Sorry to correct you but the 85,86,&87 250es Big Reds all had kickstarts as backups.

I had a brand new 85 with the cold start problem using the electric start but it always started easily with the kickstart.

The dealer at the time told me it was an "airlock problem" and when I kickstarted it the the trike would rock a bit and the air bubble in the carb moved and let it start.

I still don`t know if I should believe that or not. i still think it is the starter jet being too small.

[sportvette]

just keep it with the high compression. that bike must be wicked fast. 8)

[edog]

I bored out my cylinder head .80.My trike is a 1985 225dxn tri moto with electric start.If i try to pull start it by hand it doesn't even move.Then if im lucky i can flip the decompression valve then pull it.Hurts my hand when i do it.I flip the decompression valve Then press the electric start button.I allways have to have the battery charged to 13 volts to acomplish starting it.You should see the 8 inch long blue flame that comes out of the end of the exhaust pipe when you rev it up.It's a cobra exhuast.I also have to use a hair dryer to warm up the carbarator,or when it's cold the thing will never start.



edog was here

[eh_tee_see]

hahahha, edog thats tight.

[terdburgler03]

if they sell these pistons in denniskirk then i woundnt worry about it but that is wicked hight for a 4 stroke you say it had a cam shure its the right one sounds like there might be a case of bad valve over lap but i would keep running it with good senthic oil up in the crank idd take 15 thostants off the head see if i can get that shat hitten 300 that trick would get in in every magizine around a 300 psi 4 stroke

[YTZ250#1]

Will be puting a new top end on this one.One of you guys that say just run it,well you get yours up that high and let me know how long the bottom end lasts.Can you say big bang,Klunk,poofh?Be sure to let me know how much it costs for new cases and crank kit,I'm pretty sure the rod will be sticking out the case somewhere. :D :D

[edog]

that"s got to hurt. :x

[mudduck14843]

Will be puting a new top end on this one.One of you guys that say just run it,well you get yours up that high and let me know how long the bottom end lasts.Can you say big bang,Klunk,poofh?Be sure to let me know how much it costs for new cases and crank kit,I'm pretty sure the rod will be sticking out the case somewhere. :D :D

200x over 200 psi comp. been running it for almost a year now
cost for cases crank kit $0.00

[TRI Z Racer]

Well from my information on turbochargers and compression ratios, you can increase the boost into an engine with a turbo to a point and not have to beef up engine compponents such as cranks and whatnot, granted the higher the compression the higher the octane fuel you must run to avoid detonation. Its RPM's that will grenade a lower end. The forces on the crankshaft and main bearings are increased exponentially as RPMs increase by 750, not by compression. SO as long as there is no detonation, and it starts and sounds good, then he shouldnt have too much of a problem.