250-500cc GasGas piston in WR 300

[MOTORHEAD]

I took this pic of a '97-'01 Honda CR250 race piston from SRS racing, because it has a different skirt than the stock Honda piston, which is much like the Husky piston and I was thinking it was much narrower. The skirt is narrower, but not as narrow as the GASGAS piston. Anyway, they did work OK in the older Honda cylinder reed motors. I could actually probable run this piston in my WR250, but it's been a pen holder for a long time now.

Relevance? I don't know, just thought I'd share.

 

[Motosportz]

Thank you!

The Wossner piston looks like it has a wider skirt on the intake side than the Wiseco. If you have a chance can you drop the piston into the cylinder and see if the skirt is wider than the intake port at its largest opening? Or more simply can the intake skirt fit into the intake port as it passes?

The Wiseco comes to a narrow point and it can fit into the port, which worries me.


Against my better judgment I installed it last night. It turns over just fine and feels great, but that intake skirt makes me nervous. I'm going to run it for a bit and then change it out for a Vertex on an accelerated time frame (assuming the Vertex intake skirt clears the port).

On a positive note the compression is up quite a bit. I can really feel it in the kick starter. And I can actually get a squish measurement with .125" solder. My caliper is a Harbor Freight hunk of junk that only measures down to mm's, but I believe it to be around 1.6-1.7mm's, which puts the squish around .067-.070". Not ideal, but a lot better than .125"+.

Need a new head bolt and exhaust o-ring before buttoning her up, but should have those today and hopefully go for a ride tonight. Will report back.

Roll the dice baby.

 

[PC.]

Roll the dice baby.

It's just money..... (I'm sure the Husky brass love reading that!)



That's an interesting piston Motorhead. What's the story with the holes? Exhaust bridge relief?

The skirt looks nice and wide to me. Look at the pic of the Wiseco on the last page.
It's like an ice pick!

 

[MOTORHEAD]

The holes are boost ports, that's the intake side. It's a boost ported, flat top single ring piston for lots of top end.

I remembered the skirt being narrower than the stock piston and a lot different than stock.

I intended to make you feel better about running the GASGAS piston with the narrow skirt by showing you the Honda piston was similar, but it's not early as drastic.

I think that piston it made be Vertex, but I'm not sure.

 

[PeterHB]

I took this pic of a '97-'01 Honda CR250 race piston from SRS racing, because it has a different skirt than the stock Honda piston, which is much like the Husky piston and I was thinking it was much narrower. The skirt is narrower, but not as narrow as the GASGAS piston. Anyway, they did work OK in the older Honda cylinder reed motors. I could actually probable run this piston in my WR250, but it's been a pen holder for a long time now.

Relevance? I don't know, just thought I'd share.

Honda SRS piston for Honda 125 bike is a stock Husky 125 piston!!

 

[Johnnymannen]

I made some measurements on the Wössner/GasGas piston i have here, and 5mm up on the intakeskirt it´s 35mm wide, 10mm up it´s about 41mm wide, 15mm up it´s about 52mm wide. before it starts to round off at the bottom it 27mm wide.

 

[MOTORHEAD]

Honda SRS piston for Honda 125 bike is a stock Husky 125 piston!!

That's interesting.

But, I'm not surprized. 125 Husky's have been faster than 125 Hondas for a long time.

 

[PC.]

It runs.

I buttoned her up, filled the tank and she fired to life. I warmed it to operating temp and went for a little rip around the neighborhood.
She's not slow, but it was not an eye opening experience vs. stock. Although its hard to tell when I'm pussyfooting around the hood trying to avoid police intervention.

It's quite a bit warmer here than last time I rode it, so the jetting is super fat (especially the pilot) and the response was pretty sluggish, but once past the pilot circuit she was motoring just fine.

The truck is all loaded and I'm outa here in 30 minutes for a real test.


Thanks for the measurements Johnny****************************************
When I tear it down for inspection I'll measure the Wiseco and see how it compares.

 

[Johnnymannen]

It runs.

I buttoned her up, filled the tank and she fired to life. I warmed it to operating temp and went for a little rip around the neighborhood.
She's not slow, but it was not an eye opening experience vs. stock. Although its hard to tell when I'm pussyfooting around the hood trying to avoid police intervention.

It's quite a bit warmer here than last time I rode it, so the jetting is super fat (especially the pilot) and the response was pretty sluggish, but once past the pilot circuit she was motoring just fine.

The truck is all loaded and I'm outa here in 30 minutes for a real test.


Thanks for the measurements Johnny****************************************
When I tear it down for inspection I'll measure the Wiseco and see how it compares.

Good luck in your weekend race! looking forward to hear from you after the race!

Johnny:sweden:

 

[PC.]

I had pretty high expectations and I must say that I am impressed. A little compression woke this motor right up. The docile laziness that used to occupy the first 1/3 of throttle pull is gone and now she jumps right into the power (So much for my initial thoughts!). The bike still chugs and grunts like a champ, but it takes a conscience effort to maintain throttle control now as where I used to not even think about it since the motor didn't really make big power until around half throttle.

I heard a little knock when chopping the throttle during my 100yd full throttle testing sprints, but a 1/2 turn in on the air screw mostly cured it. I was real concerned it was piston slap, but it was just lean on the bottom. It was quite a bit cooler in the mtns and the jetting felt real good there.

I didn't put much time on it (maybe 40mins run time), but I'm going to pull the reeds and see how the intake port edge looks. If it looks perfect then I'll button her back up and race it on Sunday.

In addition to the piston I put in a CEL needle in the 3rd groove and replaced the too-long throttle cable with an 99 Honda CR one (thanks Mark! It works perfect), so this may have contributed to the low end snap, but there is no denying the bike is making more horsepower. Top end feels similar, but its not a defined transition anymore. Now she hits hard early and seamlessly transitions into the top end. Great mod for the power mongers.

Current specs:
domed piston
PC pipe/silencer
PWK 38 (175, 45, CEL #3)


Johnny.
get to work! I want to hear your impressions.

 

[MOTORHEAD]

Now you need to get hold of WISECO and have them run off a batch of GASGAS pistons with Husky skirts.

Somebody like HALL's would have the clout to get it done. They can sell them as "RACES CHOICE" pistons.

 

[Motosportz]

If it looks perfect then I'll button her back up and race it on Sunday.

Devilshead? Shane and Jake will be there too. should be a good turn out of huskys. I will not be there as i am taking the fem camp / riding this weekend. Have fun.

BTW, you are nuts, your 300 needs more power like my 125 needs to be lighter.

Wonder if the is a GG 250 piston that does the same for the WR250?

 

[PC.]

Now you need to get hold of WISECO and have them run off a batch of GASGAS pistons with Husky skirts.

Somebody like HALL's would have the clout to get it done. They can sell them as "RACES CHOICE" pistons.

Wiseco is on my list right now. I called them last Thursday and spoke with a gentleman whom was supposed to check all their 72mm piston specs and advise if they make such a piston, but he never called back.

I also emailed them Monday asking the same question and even I supplied the part numbers for all their 72mm 2 stroke pistons. Still no response. I guess they dont need/want the business

Devilshead? Shane and Jake will be there too. should be a good turn out of huskys. I will not be there as i am taking the fem camp / riding this weekend. Have fun.

BTW, you are nuts, your 300 needs more power like my 125 needs to be lighter.

Wonder if the is a GG 250 piston that does the same for the WR250?

Yeah, the Devilshead. Cliff will be there too.

The bike wasn't exactly hurting for power, but it was in there and easy enough to coax out. I consider this as fixing the factory flaws. Still need to get the head worked, but that can wait until I'm accustomed to the new state of tune.

I think back to my (and your) 1st ride on this bike at Jones Creek and how it compares to its current state and I think you're going to be shocked next time you ride it.

Have fun this weekend!

 

[Motosportz]

I think back to my (and your) 1st ride on this bike at Jones Creek and how it compares to its current state and I think you're going to be shocked next time you ride it.

I'm sure you are right.

 

[PC.]

I did not race on Sunday as I once planned, but I did get the bike out for some seat time. It runs good and certainly feels stronger down low, but I am getting piston slap so it's getting axed.

I put about an hour on it in the trails and I actually prefer how the stock power delivery was. Very subtle and forgiving down low and then heavy power once on the pipe. For ice and road racing power is king, so you may love it Johnny, but it makes the bike more work in the woods. I'm going to get an OEM-spec piston, have the head cut for it and be happy.

 

[Johnnymannen]

Ok, thanks for that info Brandon. I have some hours left on my piston, so maybe i change later in the autumn. I bet it would be great when i go iceracing or on the street! Maybe it´could be adjusted with jetting a bit for the woods to make it more gentle on light throttle, using another needle. have you thought of changing the throttlecam? Maybe that would be a good thing to make it more manageable in the woods

Johnny.

 

[Motosportz]

I put about an hour on it in the trails and I actually prefer how the stock power delivery was. Very subtle and forgiving down low and then heavy power once on the pipe. For ice and road racing power is king, so you may love it Johnny, but it makes the bike more work in the woods. I'm going to get an OEM-spec piston, have the head cut for it and be happy.

thats what I love about the WR motors, mellow on the bottom for the nasty stuff and flat rips on top when it is time to get a move on.

 

[rasputin]

Now you need to get hold of WISECO and have them run off a batch of GASGAS pistons with Husky skirts.

there's nothing wrong with vertex pistons, they're one of the top brands for pistons (they worked very hard in the last couple of years to get where they are now).

r

 

[hrc630]

PC, you can try a Power Now +, on my bike this little piece of metal make a really good powerband. Also, for me the EEL needle is better than the CEL.

Also i have read some post here about the longevity of the piston on the WR300. When i have work on the head, my bike have about 75 hours and the cylinder look brand new. I will change the piston at about 150h, not before that. On a big bore two stroke with good oil and clean air filter the piston can last very long. On my previous CR500 i have change the piston 2 times in 450 hours. I dont see why the Husky need more frequent change.

 

[PC.]

My piston was pretty much done at 70hrs. The intake window on the cylinder had worn a deep groove into it and the rings were starting to show blow-by. If it were a cast piston that was not grooved I'd consider re-ringing it, but mine was done.

I think I like this CEL needle, but I need some more time to really tell. For me, it's better than the DDK, CEK or N3EJ (yami needle) that I've tried. Those all felt dead on the low end.

Is the only option for an OEM replacement other than the Vertex piston that comes stock? I dont see anything on Vertex or Wossner's site for a WR300 piston (even though Vertex made the stocker ).