PROJECT: yfs250r official build thread

May 11, 2024
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10
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Utah
Welcome to the official build thread for PROJECT: yfs250r

PROJECT YFS250r is about making the quad Yamaha should have made, a trx250r and lt250r competitor.

This is being accomplished by swapping in a 250 2 stroke from a dirt bike into a heavily modified blaster chassis. The chassis will be stripped down, gussets and other bracing will be welded in for support as well as slight adjustments to the frame to help its ride better. The benchmark for suspension is for it to out handle a modern 450. 18.5 inch shocks will be used in the front with a custom rear end which will be based directly around phragles blastersaurus which won the Baja 1000.

Testing will be done through different stages in the build. Since it is a non running roller the first test will be after the 250 motor is swapped in, with stock suspension, stock brakes, etc. A Baja style pre determined course through the Utah desert will be ridden and timed. Anytime a major mod is added it will be taken out and timed. We will be testing it against various stock 450s. Once the baseline has been hit and it has beaten a stock 450, the final test will come. It will be timed against a built trx250 with long travel suspension.

Until the goal has been reached this project will not end. Continues modding will be done until the desired result.

The question has been asked, why a blaster? Why not a yfz450 250 swap or a banshee? The main reason for this is weight. Blaster are extremely light even after they have been stretched out to the dimensions of a normal quad. The small frame helps keep weight down as well as the air cooled 200, however it will be heavier with the liquid cooled 250. The target weight for this build is 339lbs… the weight of the 250r that it is being tested against. While claimed weight of 450s is anywhere from 340-380 anyone that’s ever weighed them knows this is not true, most weigh in at about 400 or even more just as a stock 250r supposedly weighs 330 however a fully built one with light weight parts weighs at 339. While the 450s are heavy due to the 4 stroke engine you can’t get around the fact that a blaster frame is much smaller and therefore lighter.

The second reason for choosing a blaster is price, while a blaster needs much more work to get it up to snuff the price of 400$ for a nice non running quad with good plastics, seat, etc just couldn’t be beat.

This thread will be updated regularly with everything done to it, explained in detail

I will explain in detail how each step is done for you that wish to attempt the same thing.

A link for youtube will also be here when the first video comes out for you visual learners. The videos will be direct and to the point as are for informational purposes.
 
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first things first… the rolling chassis. I picked this 1993 blaster up for 400$. It needs a top end (or that’s what I was told). Good condition cosmetically and chassis wise which is all I was after.

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Apon furthar inspection of the motor there is no rebuilding it and dropping it in a go kart like I was hoping… oh well.

There is a chip taken out of the case as well as a home made stator cover
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the blaster was picked up yesterday and today I have torn it down to a roller. Waiting on a sand blaster and gusset kit to arrive in the mail. Next step will be prepping the frame to handle all that unbalanced power.

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