Big Bore Kit,if it worth it?

I'm semi-interested in getting a big bore kit for my 2012, I plan on keeping the bike for a little while longer as it's served me well but I want some more power and pep with the bike. I've taken quick looks online at some of KTM's 500cc and 690cc bikes that are road legal but I like the idea of having a 250cc under insurance (21 but fully licenced,5 years riding) and not having to go through the process of selling a bike and travelling all over to look at new bikes. Is it worth it to spend 1G on a big bore kit or would it be more feasible to just purchase a larger bike? Those of you that have your bikes bored out to 290, would you recommend it?

Thanks in advance!

I guess that would depend on what adding some horsepower/torque through the range is worth to you. More horsepower is generally a good thing, but it isn't cheap and can come at the cost of reliability, fuel economy, etc.

The Euro 500s and their kin are fast, but they are expensive and maintenance intensive. They are nice and light though,

The 690 is like a much more powerful WR250R/X but is a bit heavier, and expensive.

I considered these bikes when shopping for my 250, but it really came down to me not wanting to deal with the maintenance schedules. I liked Betas the best for what it is worth. For me, the power is nice, but it's more of a novelty outside of competition.

A few years back I managed to blow sand through my engine and decided to do a big bore for the rebuild. It wasn't worth it. Sure it had some more power, but it makes the bike have more vibrations. Basically it will no longer feel like a WRR. In the end I scorched the cylinder due to my programmer being slightly off. Disgusted with myself I left the bike with my cousin, told him to part it out and he could keep 1/2. He actually rebuilt it to factory spec and gave it back to me. I once again love my WRR.

My advice, if you want/need bigger bike power save yourself the headache, sell the WRR and buy a bigger bike. If you want a little more power, airbox mods with pipe and exhaust help some, but you have to accept that this is a 250cc bike that was built for reliability, not racing.

Here is what I have learned modding my 2012 WRR and then comparing it to a 2008 with the TR280 kit...

First thing I would do is get the Ergos right for you. Most of this is free, just adjustments and the like.

I would change the stock gearing to something like 13/47 or 13/48.

For me the next thing would be the seat and after that a cheap rack and a skid plate followed up by a rad guard. My ass is old and really did not like that stock seat.

After that I would have the suspension done. For me it was GoRace - my buddy went with RaceTech. Both work really well and transform the handling of the bike especially if you are a bigger guy. I have heard Konflict also does some good work as well.

Last thing I would touch are engine mods since the return on investment is pretty low. If I should need to rebuild my engine I may go that route.

I had the chance to ride my bike (pretty much stock motor) back to back with a TR 280 kit. I really could not tell that much of a difference power wise. But the TR 280 was running stock gearing and I was running 13/48 so I know there must have been an improvement with the 280 kit since it ran as well as my stock bike with lower gearing.

However the biggest issue I had was the stock suspension on the 280 bike. It bucked me all over the place and did not allow you to ride a smooth or as quick through rough trails. You may have had more power but you couldn't use it.

So I think part of this is what you use the bike for. If you are running a lot of 2 track and having to put street miles in to get there then I can see where a big bore kit may come in handy. But I would figure around $2000 to have everything done since if you are going that deep into the motor you should probably clean up a few other things as well - head porting, etc.

To put this into perspective... I bought a street legal 2003 KTM 450 EXC (rfs motor) for $2500. I am pretty sure that a WRR with a big bore kit would not touch that KTM power wise. Now service intervals is a different issue.

first, don't do BB without having done suspension. that is biggest bang for buck....

I recently had my 37k mile 08 overhauled and decided to upgrade to  big bore and stroker crank.  Bike had powerbomb, Q4, airbox, 13/48 etc already done. (similar to Daisychain on youtube)  Athena 290 + crank= 306CC I'm calling it a WR310R now.


performance wise, well.. the bike is "more" everywhere in the powerband. Not a monster, but better everywhere and to me it finally feels like I don't have to ride in  high rpm to get performance..

If you are doing the BB, do the stroker crank too.

very happy.

Thanks for the input guys! I've got a lot to think about now. Unfortunately, my bike was recently stolen and vandalized so this definitely helps with helping me decide what to do when insurance gets back to me on their decision; I didn't think the suspension would play that large of a part in how it impacts my riding. If insurance allows me to fix it I'll definitely so a suspension and gearing upgrade.

Cheers, Neil

This sucks. I hope that the insurance don't total it.

Potentate wrote:

Disgusted with myself I left the bike with my cousin, told him to part it out and he could keep 1/2. He actually rebuilt it to factory spec and gave it back to me. I once again love my WRR.

What an awesome cousin!

First theres the athena big bore, and thumper racing. They are a little different.

As far as having vibs after a big bore, have the engine balanced when you do it.

Stillwater97 wrote:

If you are doing the BB, do the stroker crank too.

very happy.

Daisy chain got finished right, balanced and some unique porting, unless I'm thinking of the wrong build. A lot more to this operation than sticking a bigger piston in with a new crank and calling it good. I don't think they make gas that won't detonate off the compression that thing is making without removing some of the head.

beer goggle wrote:

What an awesome cousin!

I know, I was shocked and appreciative!

So in my earlier reply I stated that it may be possible to buy another bike with more HP and comparable suspension. The example I gave was my 2003 KTM 450 EXC that I picked up for $2500 and sold later for $2500.

Well it turns my friend who bought it from me wasn't riding it very often. I believe in the 4 or 5 years he had it he has ridden it twice. So the bottom line is I just bought the bike back and am looking forward once again to enjoying that RFS performance. Got a couple of little upgrades for it in the works and a couple of rides planned.

Best part is when I offered $2500 he countered with a LOWER price - I guess we both suck at negotiation tactics.

Then again another friend and I were passing a GasGas XC250 between us a few times. One of us would buy it and update the bike a little and then sell it back to the other in a year or so for like $200 less than what we paid for it. That was actually pretty funny since the other guys in the riding group wanted a piece of that action for a bit.