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Discussion in 'Thumpers' started by DisTech, Nov 27, 2009.
Good stuff man!
Ya know DisTech, that what i love about your threads is the good pics & easy explanations, the moving gifs are just a bonus
Keep it up my son
The piston will hit the cylinder head with zero clearance besides the piston would have to protrude out of the cylinder by the head gasket thickness.
Even a titanium con rod would only allow a safe 0.9mm squish measurement.
To set it properly at around 1mm it is better to measure the clearance then machine the lower gasket surface as needed to get the clearance and retain a steel base gasket..imho.
Some race kit parts have selective base and head gaskets to set both compression and squish.
Machining the lower gasket face eliminates any possible damage to the bore coating.
Bloddy hell Les your a clever ol boy, Kiwi "know how" eh?
you can also take apart the stock 3 piece head gasket, by drilling the 2 riviots and use 1 of the 3 to rase the comp for next to nothing. this is what i did befoe puting in bigbore kit ,gave a good hit of power.
that was my point.
i should of said that it was zero decked, i think anyone atempting to build or modify an engine know, there has to be room for valves to open and for metal to expand as it heats up, if they do not know this then they should not atempt to modify there engine without some more experenced preson to over see project. it is not rocket science, but you do need to know how a engine works, so you do not blow up your engine.
Just sent Jesse triples, busted 93 cylinder, 94 head, 94 rocker cover and DR650 TwoBrothers mid tube (but that's for another thread).
I also sent MegaCycle the 94 rockers for weld and grind and they should send them back with a new billet core cam!
Stock______________.328/.328__226°/226° @ 0.040"
Web Cam 223_______.335/.335__240°/240° @ 0.050"
Megacycle 31705____.372/.372__236°/236° @ 0.040"
The stock valves are 30/27. New seats and new Kibblewhite valves will be 33/30.
Once these parts come back I should have one complete motor.
Need to start looking at the 93 basket case. If the guts don't look to bad (and I can figure out how they go back together) and I find a rocker cover for the 99 head then motor number two should come together.
Please tell me more about the head work you had done. Did you have the intake enlarged?
Sorry it was just a general statement.
As you know i am sure,most people have no idea what squish clearance is and how such a small thing can improve overall combustion.
I wasn't trying to attack you or anything.
I just wanted it made clear that I already knew that!
& I totally agree with you, engine talk is a totally different language to the majority of people.
to fit the fcr carb i mounted intake then marked the metal needed to be removed and remved as little as posable. porting all i did was clean up casting flaws and seats, hand lapped valves as well.
Cool, thanks for the info. I may ask you later about jetting the FCR37.
Digging into the 93 basket case.
looks like there's a little bit of metal in there.....
but that won't slow you down much.
DisTech, in the upper left corner of the second picture, it looks like there is a previous repair on the inside of the case. Is that so? Could that be the source of the debris? Is there something there that rubs on it?
Good eye Jay! I was thinking to myself those little shards look like die grinder shavings. I'll bet that's where they came from, trimming up the repaired area.
Is this the motor that broke the rod? What does the rod look like? Did it actually snap? That could explain the metal shavings and marks on the case. Looking good, though! Those KTM forks look very nice.
Shop vac got most of the visible stuff. The stuff that was a real bitch was in the bearings. Some of the bearings wouldn't even turn. I used a lot of carb cleaner to blast/flush them out.
And yea I thought it was odd too that the visible stuff looked like shavings, but the stuff that was in the bearings was more like chunks of aluminum.
Yes, good eye Jay! This photo makes it look worse than it is but I still can't believe I didn't see it until you prompted me to look closer!
Yes, the 93 is the one that broke the rod and when I first saw the shavings that's what I thought. Thanks, I hope they perform as good as they look. Someone in here called em boingers!?!?
Picking through the baskets I came across the valves and the remains of the piston. Also, that's a 12 tooth CS sprocket. Pretty low isn't it?