Vintage Dirt Bike Q & A

ok bought the bike in pieces put it together fresh fluids everythins was there except for some nuts and bolts... so i got it started runs pretty good...but it is a pita to start after my feet were spent from the kickback. my dad tryed and he broke his foot. what can i do to fix this my dad said timing.. how would i go about fixing the hardcore kickback? bii dont want to break my feet every time i try to ride bike was sitting for at least 3 years before i got it...and clutch is frozen. but other than that. its not to bad for what i got into it. it has decent but not great compression.

i might suggest a dial indicator to set the timing,presuming the timing is adjustable.

as a CR model i would think it has electronic ignition and hopefully either the Pulsar or the stator plate can be adjusted.

here is a video on the use of a dial indicator used on my 1975 CR250M1
i used a Fluke 88 in place of a buzz box since it has breaker points and i had no buzz box available at the time.


a CDI requires no buzz box so if the timing is adjustable and it has marks to use then you are set but if you alter the timing a dial indicator is a must.here is where you can get one and you may need the extender if your engine is air cooled.
http://www.hvccycle.net/tools/

scroll down a ways to near bottom and you will see the dial indicator and adapter set for air cooled engines.

i think yours is liquid cooled and only the CR500 was air cooled that year if memory serves.

if the timing is in spec and can't be adjusted the only thing i can suggest is wearing a boot and build your leg muscles.that is all i can offer here.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

I tried to get one over the weekend from a local tool store...but it didnt have threads to put in the spark plug hole... and i checked the stator plate and it was off a tiny bit from the factory marks.. it has a brand new stator and coil... my ankle hurts to bad to try anymore gotta let it heal a little.. tried bump starting with no luck...thanks for the reply.

well today i took the motor out... turns out had a head gasket leak.. and i wanted to look into the clutch... also found out it has a brand new wiseco prolite piston 67.50mm bore... and its been ported...what cc does that make it? i figured i got it down i might as well do it all but dont need a piston.. so just gonna service the clutch and new gaskets...

stock bore and stroke is 66 mm x 72 mm,according to a online calculator it comes out to 257.65 cc's

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

got it all apart cleaned everything all gasket surfaces.. painted it and put it back together... fired up after the first few kicks. it came Alive.. then i shut it off wheeled it outside. tried starting it again and it just doesnt want to run even after many attempts i checked compression it had a whole 55 pounds.. had 122 before i replaced the gaskets. so i checked for a gasket leak with soapy water.. nothing. so i tore it back down ruining my fresh gaskets.. cylinder and piston looks great.... the reason i tore it back down was the possibility of the atac linkage at the bottom of the jug not being on correctly. im stumped i dont wanna throw more gaskets and it not run... should i bore it another .20 over making it a 68 mm piston. could that power valve system not being properly put back together cause that much compression loss

you might want to pull the cylinder and check for broken piston rings due to the possibility of the piston installed backwards.the ring ends goes towards the intake on the cylinder.

if the piston was installed backwards it is possible the ring end popped out and snagged the exhaust port and it did damage to the piston rings,the piston ring lands on the piston and damage to the exhaust port on the cylinder,major bummer there!

also when reassembling the top end make sure the ring ends are positioned right on the ring stops in the piston itself.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

im pretty sure the piston and rings were on correctly because i didnt take the piston off the rod... and also theres a arrow on top of the piston pointing towsrds the exhaust. and i made sure the rings were on correctly. the only thing im second guessing myself is that powervalve linkage when u pull the cylinder off that looks like it works off of the waterpump. i think im gonna replace my rings anyways and try again..i checked both the cylinder and piston with a micrometer thing cylinder was right on where it sould have been piston was just a tad smaller. the piston looks almost new with minor minor wear. cylinder walls look excelent.. i just dont understand how it came alive like that then next start up was nothing. now doing my research i picked a bad year to try to bring back because of the waterpump issues they have.. so im not trying to throw alot of money into it... as of now i have 250 in it with purchase. and im really not trying to go past 500 because of those right side cases

little of the work ive done.

well dave u were right on the rings.. it was hard to catch but one of the rings had a chip right where they come together bought new rings and gaskets and now its running excellent.... thanks alot...will post pics of finshed produc... didnt do a full resto just repainted some things... still need to strip the ank.