So since I'm getting back into the sport after about 10yrs out of it, I bought a couple LT250r's.
Im a 2-stroke guy forever. Wasn't gonna buy a four stroke. Wasn't gonna buy a trx250r cause everybody around where I live think they are made out of gold. Worn out, rusty gold. $$$$
So I bought 2 lts for less than the price of one non running trx.
One had a great running motor, the other a nice frame and chassis.
I decided to build the other motor, and I wanna build it all myself. From the bottom up. I want to squeeze every ounce of power possible out of every crevice within that motor...
So I find the 2-stroke handbook. Looks like gospel to me and I was taking as such until (on a previous thread) itwas brought to my attention that many of the formulas and theories within the book were later proven wrong. I knew the book was outdated, (bikes werent liquid cooled back then) but I didn't know some of the other info wasn't so accurate.
So what books should I read? I want serious formulas. I want real theories. Which ones u guys like?
Thanks bad moon! Looks like good info. Lots of pictures too, which always helps. Got my new crankshaft today. Got a unbelievable deal on it. Hot rods crank assembly BNIB $100! I probably didn't really need a new one, but I got it anyway. Now all I need is piston kit(still undecided on re-pinned YZ piston or LT piston and thrust washers.),main bearings, gaskets and seals, an inside mic, a degree wheel, and a fancy 90* rotary tool.
check the run out on the crankshaft..even if its new. Get the pin welded also.
check the run out on the crankshaft..even if its new. Get the pin welded also.
Why weld the pin on the 250s. We rebuild hundreds of cranks each year. The 250s do not have a history of the cranks moving unless someone has stroked the crank. Unnecessary welding of the crank pin adds considerable cost to future rebuilds and those cranks that have the crank pin welded do not usually true up as well as non welded cranks.
The stroked cranks need to be welded because the crank pin holes are not heat treated after the new crank pin hole is machined in the crank web. The press fit on the crank pin holes is usually reduced to prevent the crank from cracking through the pin hole. The loose fit on the crank pin hole is another reason stroked cranks need to be welded.
We weld cranks when the press fit is too loose but do not recommend it on a crank that has a good press fit.
Im reading Alexander Graham Bells, Two Stroke Performance Tuning book that I got off of amazon.
Well, I've heard that by the time Alexander graham bell had finished inventing the telephone, he already had 2 missed calls from Chuck Norris.
Had to throw the chuck Norris joke in there. I just hope chuck Norris don't think I'm making fun of him. He's awesome. I've heard he don't even flush the toilet.. He scares the $h/t out of it!!
But thanks crash lander, is the book pretty in depth as far as porting, port timing, compression, ect? Do u like it? I've considered ordering that one my self.
This book covers the gambit of 2 strokes but is not the guide to building an absolute terror. What I am getting out of it and what knowledge I have been kicked is really to blueprint the engine first.
It does have dyno graphs of oil mixture tests, explains squish, even discusses pipe design. Anything you would want to do is in that book, might be a different engine but still a 2 stroke and like I said, the most fun, long lasting setup, a simple blueprinted engine.
Early on in the book he describes a race engine with porting and a pipe combination that was suppose to be
**** but it went belly up for a stock cylinder because the power band was wider and able to be ridden making the bike all around faster.
There is somewhere to download it for free but I wanted to have a hard copy to get greasy.
Awesome Crashlander! I'm gonna order that book on payday, along with my crank bearings. I have a hot rods crank, which bearings do you think I should get? Hot Rods? Or OEM? I want the best.
OEM bearings are the best and have the correct internal clearances.
Remember to go thru Honda east Toledo, Jason/yuhuza is a member here. In his signature there was a discount code also. Very helpful and has good prices...
I ordered all of my bearing from Yuhuza out of East Toledo. I ordered just about anything i could think of needing and it showed up about a week later. Only OEM for this rebuild minus the gaskets.