Project Big Bore

Well I just finished dropping my bike off at Thumper Racing to use as a guinea pig for designing a new big bore kit for the WR250R/X. My bike will be there for the next week or so during which they'll tear down the motor, take measurements and specs. Afterwords, the specs will be submitted to the piston designer and the kit will be engineered over the course of the next few months.

I don't know a whole lot more at this point other than there goal is for a 290cc kit. I'll keep everyone updated on the progress.

- Dave

Dave you'll end up with a kick ass bike when they are done...sweet deal or what?!!

Sounds really interesting. You'll have to keep us posted.

SheWolf wrote:

Dave you'll end up with a kick ass bike when they are done...sweet deal or what?!!

Heck yeah I will! Not only are they installing the big bore upgrade but they are going to add some extras like exhaust, tires, etc. Not a bad deal at all -- I feel like I won the lottery or something lol.

What kind of warranty (if any) are they giving you on the upgrade? Because this will probably void any factory warranty you have left. The extra goodies for your troubles is a nice perk, but later down the road if you have problems with the engine are they going to fix it for free? Just curious.

mwakey wrote:

What kind of warranty (if any) are they giving you on the upgrade? Because this will probably void any factory warranty you have left. The extra goodies for your troubles is a nice perk, but later down the road if you have problems with the engine are they going to fix it for free? Just curious.

We really didn't discuss that but I'm not really all that concerned. I did some research and looked at other projects Thumper Racing has completed and all their work appears to be top notch. They've been in business over 15 years. I've heard nothing but good remarks regarding there existing kits for other bikes. They are very local to me (within 3 miles or so) so if I have issues I'm sure they can be worked out.

It doesn't need a warranty, its a Yamaha

Bet you are looking forward to getting it back to given it a good test, I'm looking forward to hear the results think its wot the wr needs

Update?

Yeah... Any updates for us?

Well... He could be out giving it a thorough test. Guess all we can do is wait.

I got my bike back last week (it took longer than expected for the motor tear-down and measurement process) and we are waiting for the parts to be fabricated (sleeve, piston, etc.). I wasn't given a definite time frame on when these will all be finished, hopefully within a month or two. They will call me and let me know once everything is ready to go at which time I'll bring my bike back to them for installation and testing.

Can't wait for the final outcome on that puppy. Thanks for keeping us updated.

Any update yet?
looking forward to this one.

Bump

Not much to report I'm afraid. The shop doing the work, Thumper Racing is still waiting to get everything back in. Since they are doing a full build-up of the bike (pipe, suspension, bars, graphics, etc.) in addition to the big-bore kit, I'd imagine it's taking longer than expected. We made it clear that I wouldn't bring it back in until everything is ready to go, to minimize the time they have the bike.

No need to keep bumping - I will keep everyone up to date as much as possible.

Well after many delays, I'm happy to report my bikes back in their shop getting the kit installed.

From what I gathered, it shouldn't take more than a few weeks to complete. After that I will need to wait a bit longer for the magazine photo-shoot and write-up.

He's not sure what magazine will cover it. He did mention that there was strong interest from Dirt Rider. I will post more as we go.

Just make sure your bike gets the shots and not the skinny anorexic model they might put on it.

The skinny anorexic model is handy when they're posing on something you're not really interested in. In this case though, I'd rather have close ups of the engine. Preferably some good close-ups of the internal engine parts so we can see what the kit is like! Then follow it up with some dyno charts!







Oooops. Missed a spot again, didn't I ...

Oh my!

I stopped by the shop today to observe the progress on the big bore kit. At first I had a hard time figuring out where my bike was and was shocked when they finally pointed it out.
I hardly recognized it!!!

One of the techs was just finishing up re-installation of the suspension. The suspension was redone by ESP. From what I understand, the forks and shock where re-valved and re-sprung. The full FMF exhaust system was installed and they were still in the process of tuning it. The big bore kit was already installed and from the outside of the motor, you couldn't tell anything had changed. A host of other changes where done and i dont really feel like typing out each one.

Not long after seeing me standing there drooling in disbelief, the tech fired her up and let me take it on a quick rip around the premises. OMG is about all I could think and say. Of course this isn't a comprehensive review by any means as i only got to spend a short time on it and it wasn't even fully dialed in yet but it was amazing nevertheless.

Power felt like it was increased everywhere, low-end especially. The bike wanted to wheely in every gear, completely different than what I was used to. I'm a rather heavy guy (195lbs) and I could feel the power and torque was defintely improved through all ranges. The exhaust note was defintely throatier (I know what the PC4 sounds like on the stock motor) and the bite defintely matched the bark. The suspension felt miles better, really smoothed out. I was simply blown away.

Like I said this isn't a comprehensive review by any means but just given a little taste my attitude towards this bike has taken a 180 turn. My biggest gripe were always power, suspension, and weight. The mods done do this bike have adressed the power and suspension which are easily on par or, perhaps, dare I say better, than a stock WR250F, a bike i have owned previously. I'm guessing after a dyno, we can expect over 30hp easy.

i can't wait to post a final review with pics, prepare to be amazed.

Did they give an idea of when it would be done??? I'm waiting for some reviews on the kit to pull the trigger. What magazine is it going to be in?

Sweet can't wait for the review. Did you say they were going to have it in a magazine? I sent a pm to Travis I think it is on TT to post on this site in the vendor section or somewhere on the forum if he wants to.

They aren't sure which magazine will do the review, but there is speculation it maybe Dirt Rider, as those editors have expressed some interest in the past. We should know more in the next few weeks. The kits should be available for purchase real soon.

http://www.supermotojunkie.com/showpost.php?p=878076&postcount=99

pricing for big bore kit from thumper racing.

290 CC big bore kit from Big Bore Thumpers. Includes a new cylinder for $699.00...


http://www.bigborethumpers.com/athena.html


The word has it ..... Yamaha will offer this same kit as a GYTR part and charge $949.00 for it.

Note how a Husky TE250 can get 43 hp out of the 300 kit and we can only get 30 hp out of our WRR's with a 290 kit on them. What's with that???

Greg

big bore and thumper racing are 2 different companies. i'm still waiting to see TR's dyno results. especially since powercommander is going to do map for them on the 30th.