Fully ported head

I have one! Just got it back from KWS Motorsports. Can't wait to get this on the motor along with my new Thumper Racing 83mm piston. With this, I will have done everything possible to the motor short of a stroker kit and cams. All motor, no forced induction. Once it is broken in I'm springing for a Dyno run to really get it dialed in. I think with all of my mods I could be approaching 40hp.

New Valves:



Ported intake:



Ported exhaust:



How long do you think it will take for me to blow it up?

Is it possible that you could run it with the head before the piston install? I'm curious what kinds of gains the head job is worth. Care to share the cost of such a job?

I'd really like to see some before pics (without having to tear my bike apart).

pbnut wrote:

Is it possible that you could run it with the head before the piston install? I'm curious what kinds of gains the head job is worth. Care to share the cost of such a job?

I'd really like to see some before pics (without having to tear my bike apart).

Since I already have the Athena 290 cylinder installed, there's no chance that I'll put a stock bore cylinder/piston on for a comparo. Sorry. I trust that there would be gains to be had, however.

I'm replacing the Athena 2-ring 83mm piston with Thumper Racing's 3-ring (and lighter) piston.

The head that I had the work done on is one that I bought from a member here. My stock head is still on the bike. I'll take some picture of it when I get it off for comparison.

Price for the head work? Not cheap. You can go on KWS's web site to get an idea.

I did check out the KWS site shortly after my earlier post.

I'm anxious to hear your results though. I want more power too! The only thing I'd do different is go with the Thumper Racing stroker setup.

pbnut wrote:

I did check out the KWS site shortly after my earlier post.

I'm anxious to hear your results though. I want more power too! The only thing I'd do different is go with the Thumper Racing stroker setup.

I was to get the first TR stroker kit. When Travis first decided to develop the kit, he solicited for a donor stock cylinder to develop it over on SMJ. I was the first to get one to him, so I was promised the first kit.

The more I thought about it though, the less enthused I became about splitting the cases to install it, so I worked a deal for the piston instead.

I'll leave it to you or someone else to inform the rest of us on the merits of the stroker kit.

Hurry now, time's a'wastin'!

Yea, I remember reading all that and thinking, "that lucky dog..." And then you go and not get the stroker.

I won't be able to afford the stroker kit until this time next year...

Got some before and after flow bench numbers on that head ?

Chrispy1200 wrote:

Got some before and after flow bench numbers on that head ?

Nope.

So you're putting the new piston in the athena-cylinder? Was the athena/wössner-piston broken, if it was, you have to change the oilpump too?! What compression will you have, 12,7:1 a second time or stock?
Are the intake-valves new?

A friend have got a ported cylinderhead in his ltz400, it goes much better than my bigbore ltz465! and the works on his cylinderh. where not much more expensive than my bb-kit...

germanwr250r wrote:

So you're putting the new piston in the athena-cylinder? Was the athena/wössner-piston broken, if it was, you have to change the oilpump too?! What compression will you have, 12,7:1 a second time or stock?
Are the intake-valves new?

A friend have got a ported cylinderhead in his ltz400, it goes much better than my bigbore ltz465! and the works on his cylinderh. where not much more expensive than my bb-kit...

The Thumper Racing piston has 3 rings whereas the Athena only has 2. Longer service life. TR's piston is also lighter than the Athena, so there will be less vibration. Compression will be the same as the Athena kit.

No issues with the oil pump. Valves are all new.

The smaller valves, look as they was just cleaned. Maybe it looks only on the picture so. I asked, because.i want to install my kit now. But there are no longterm rew. with it. And yours is broken after only a few miles hard riding. I want to Check, what is broken, maybe only the bolts was not correct torqued.
I don't want to install the bb-kit if i have to make big mainterance (check pistonrings, valves) much more often than stock

germanwr250r wrote:

The smaller valves, look as they was just cleaned. Maybe it looks only on the picture so. I asked, because.i want to install my kit now. But there are no longterm rew. with it. And yours is broken after only a few miles hard riding. I want to Check, what is broken, maybe only the bolts was not correct torqued.
I don't want to install the bb-kit if i have to make big mainterance (check pistonrings, valves) much more often than stock

I don't think my failure is common among BB installations. I wouldn't let it keep you from doing one yourself. If I had it to do over again, I would have re-torqued the head bolts 500 miles or so after the installation, which I will do this time.

I won't know the exact cause of the problem until I take it apart, and that won't happen until next weekend or the weekend after that.

I don't know what your failure was, but if your hindsight is you should have re-torqued the head bolts, I assume you didn't replace them with the rebuild.

A fun fact I learned about Yamahas, at least with the offroad bikes YZs and WRs, is that when you do a top end, you replace the head bolts as they tend to stretch and it's cheap insurance to replace them. With the WRR engine being different than the others, I don't know if that is the case with this bike. But when I drop in a big bore kit, I will be sure to replace the head bolts.

YamaFling wrote:

I don't know what your failure was, but if your hindsight is you should have re-torqued the head bolts, I assume you didn't replace them with the rebuild.

A fun fact I learned about Yamahas, at least with the offroad bikes YZs and WRs, is that when you do a top end, you replace the head bolts as they tend to stretch and it's cheap insurance to replace them. With the WRR engine being different than the others, I don't know if that is the case with this bike. But when I drop in a big bore kit, I will be sure to replace the head bolts.

Excellent observation, and new head bolts have already been secured.

I would have installed new head bolts when I first did the BB kit, but the shop manual made no mention of needing them, so I reused the old ones.

My Yamaha Dealer said, that the headbolts are no spezial "streching- bolts". But he replace them, because i want it, when he installed the bb-kit. 12€ for one fucking bolt!!!

The bb-kit is installed with an other gasketset; so i have a compression of only 11,8:1 like stock... He scale compression after 200km: 12,0:1...

Have much more power, and nö very high compression. He said i would have to change to a bigger cooling-system with 12,7:1..

germanwr250r wrote:

My Yamaha Dealer said, that the headbolts are no spezial "streching- bolts". But he replace them, because i want it, when he installed the bb-kit. 12€ for one fucking bolt!!!

The bb-kit is installed with an other gasketset; so i have a compression of only 11,8:1 like stock...

I paid $40 US for the set of 4 bolts & washers. Cheap insurance, IMO.

Updates?

pbnut wrote:

Updates?

I've not done a darn thing! Last few weekends have been claimed by other duties and a splash of laziness. Hope to get to work on her this weekend.

BuilderBob wrote:

Last few weekends have been claimed by other duties and a splash of laziness.

Sounds like my life story... It's a rare event when I actually put in a solid 8-10 hours in the garage these days. I blame it on cutting back on my booze intake.

I guess I should update this thread.

I did the installation in May. To my great disappointment, the piston that I got from Thumper Racing was too small for the Athena cylinder, and rather than hassle with them for a replacement, I put the Athena piston back in.

I've not ridden the WR much since the rebuild, mostly because there is a problem with the Athena piston/cylinder. I'm getting piston slap and fuel is getting into the crankcase. Bad rings, cylinder out of round... I don't know, but I'm done with Athena. The bike runs well enough, but not as well as it should with all of the mods.

I've decided to go with Thumper Racing's 280 over bore. I already have the piston, so I'm sending them a spare cylinder for them to sleeve and bore. This will be the last time I go into this engine.

Say it isn't so! Sorry about your luck Bob. Here's to hoping you get that thing squared away and running like a top in short order.

Five more months and I should be getting my kit from Thumper Racing.

Being that you've had this beast apart once or twice I'm guessing you've got an idea of what's required for parts. What have you needed as far as parts thus far? It looks like splitting cases requires a whole lot of new parts on top of the head parts.

I haven't split the cases. Only top end work so far. For that, you need a complete top-end gasket set, oil and a filter. Throw in a weekend and a whole lot of cursing, and you're finished! ;-)

Needs a turbo!!