suzuki dt8

[casper10]

i have suzuki DT8 2 stroke which i presume is about 20 years old (but looks like new)
It would never start when i bought it. I took it apart and found the pistons rings were stuck to the piston. I free them and put the engine back together. but still wouldn't start. I have since given it to a mechanic who has stripped the engine down again replacing the gaskets ,scuffed the bores as he said it had a siezure sometime in the past. checked the reed valve is ok. The engine has a compression of about a 100 in both cylinders, the spark on both plugs is excellent, petrol is getting through. I can start it two ways
1. by using a drill onto the flywheel (not ideal).
2. or by pouring a small amaunt of oil in the cylinders ( a marine mechanic advised me to do this after the engine had been stripped down as it looses its suction/seal.by doing this it will start with the pull cord (sometimes!)
Obvisouly i need to get it going reliably, does anyone have any ideas to what the problem could be ??
PS I am using a mixture of 50:1 does this seem correct ??
I am a bit of anovice when it comes to engines !!

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by casper10 on 25/03/2004 21:50 (server time).</FONT></P>

 

[andyball]

I don't have correct compression figures to hand, but 100psi might be rather low....& could certainly cause the problems you describe.

So could carb' jets clogged with stale fuel "varnish" & weak sparks. You say the spark at the plugs looks great....have you checked that you get a spark from the end of the ht lead (w/o cap) if held 6mm from the block?.

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[casper10]

thanks for advice.
I have cleaned carb out and checked spark without cap as suggested (and spark is good)
but still the same problem persists
I have the petrol/oil mixture 50:1 does this sound correct (if it wasn't correct do you know if this could cause the problems I am encountering)
i have been advised that even with the compression at 100 it should still start


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[chippie]

It is always hard to diagnose engine problems without seeing the motor but here goes.

Two strokes rely on crankcase compression which means the crank seals must be ok. The fact that you can start it after pouring oil into it suggests that it is a compression problem you have. The high speed turnover of the electric drill would also overcome low initial compression.
The spark should be bright white, as stated should jump 6mm or so. remove any surface rust on the flywheel or pickup assembly. A few pulls of the starter in the dark should show up any spark leakage.

A further thought, I dont know what external carb adjustments that model has,but
if any, you could try turning it right in (gently) and trying to start and progressively wind out until it coughs. Or get it running and fiddle with it.
50:1 seems ok. a phone call to a dealer could verify this.

Let us know how you get on. Good Luck!

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[nevster]

When I posted a question regarding the charging circuit of my DT8 on the PBO forum the following site was suggested to me, http://www.bestofbikes.no/marine/dt_8_6.htm although in norwegian it is quite easy to discern the relevant info. this site gives the oil mixture as 100:1 which ties up with what I was told when I got the engine. Sorry I cant help on starting problem though.

Regards

Mark

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