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By Swappa,
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Grand Master

Swappa

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It's over-sprung and over-jetted with no bottom end. Graeme Brough went up three spring rates for the PO's play riding. The ride is firm to say the least.

 

Varner's recommended jetting (currently installed with porting and head mod) is safe but fat. The engine loads up rolling into turns and then hits pretty good as it finally gets over all the excess fuel. I'll most likely go leaner on the brass and reinstall the stock springs that came with it. Hopefully the shims are not too far from stock. Hopefully the porting is not mid-top as I'm the kind of guy that likes roll-on power.

 

Stepped seat is a pain. I can imagine sever monkey butt after a 3+ hrs in the saddle.

 

Galfer front rotor and steel braided line with soft black pads is very strong. The level of power from the front brake is just as good as a KTM, but without the nice modulation or progression at the lever. This may be compounding the nose-low/stinkbug stance which causes some knifing and instability.

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Grand Master

Swappa

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Well, rejet made a MASSIVE difference to the lowend. Seems as though I was correct about the bike running rich. For all of those that complain about nonliner power,a 182 main jet and 50 pilotwill deinitely give you a mid range hit. The bike runs cleaner and faster throughout but esp off the bottom.

 

Thankfully my previous jetting specs worked well with the Varner topend mods. Tested at Glen Helen with my wife and two kids in tow. Not even two flats could put a damper on my day. Next up: respring right after I fix my flats.

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Grand Master

Swappa

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Quick update: confirmed timing is at zero advance and bike is running like a champ ?

Still tuning the suspension. As purchased I was at 0.46/5.4 kg/mm and 345 cc of oil in fork and 104 mm

I tested the stock shock spring and it didn't help.  

On advice from Graeme Brough (revalve guy), i'm going to run 20cc less fork oil, 3 gal tank and try and find some sag and clicker settings to suit.

I'm also installin an OEM piston and rings next week. The guy that ported the topend prefers 100 octane fuel, but does not recommend avgas, apparently because it burns hot and beacuse the jetting will be 'all over the place because planes run lower compression'. That sounds like he's run into problems with 4ts (high comp and high heat) and transferring this 'knowledge' to my 2stroke. IMHO, YZ250s runs great on anywhere between 50% to 100% avgas cut with 91 oct.

Swap

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Grand Master

Swappa

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Just curious - how much do you weigh?  I run the same spring rates and actually the same exact oil level right now (345) - I'm around 200-205 lbs without gear.  With about 10 clicks out on the forks, I can flat land a decent sized jump and not bottom out too bad.  Just comparing notes... 

150 lb dripping wet (without riding gear).

I'm over sprung by most accounts except for the fact that I'm an expert with a 3 gal tank. I know 'm going to suffer in the square edge bumps over the course of a 2hr race. My idea of near perfect suspension is YZ250 out of the box less 10cc of oil in the forks ... but you know what they say ... the best you know is the best you've ridden and the best YZ I've ever ridden was a Ty Davis fork and shock which carried our 24hr team which ranged in weight from me at 150 to 220 plus all on the same ride height and clicker setting. The team raved about it.

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Grand Master

RockerYZWR

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150 lb dripping wet (without riding gear).

I'm over sprung by most accounts except for the fact that I'm an expert with a 3 gal tank. I know 'm going to suffer in the square edge bumps over the course of a 2hr race. My idea of near perfect suspension is YZ250 out of the box less 10cc of oil in the forks ... but you know what they say ... the best you know is the best you've ridden and the best YZ I've ever ridden was a Ty Davis fork and shock which carried our 24hr team which ranged in weight from me at 150 to 220 plus all on the same ride height and clicker setting. The team raved about it.

Amazing how rider ability and technique changes spring rate requirements...  I'm a mid-pack novice.  Thanks for the response.

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highmark00700

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Quick update: confirmed timing is at zero advance and bike is running like a champ ?

Still tuning the suspension. As purchased I was at 0.46/5.4 kg/mm and 345 cc of oil in fork and 104 mm

I tested the stock shock spring and it didn't help.  

On advice from Graeme Brough (revalve guy), i'm going to run 20cc less fork oil, 3 gal tank and try and find some sag and clicker settings to suit.

I'm also installin an OEM piston and rings next week. The guy that ported the topend prefers 100 octane fuel, but does not recommend avgas, apparently because it burns hot and beacuse the jetting will be 'all over the place because planes run lower compression'. That sounds like he's run into problems with 4ts (high comp and high heat) and transferring this 'knowledge' to my 2stroke. IMHO, YZ250s runs great on anywhere between 50% to 100% avgas cut with 91 oct.

Swap

 

I don't really agree with the underlined sentence. I have tried everything from straight 110 to a blend of 110 and pump 91, straight av gas and blending pump with av gas. Obviously every motor is different but in my 295 and my turbo sled, straight av gas is the most consistent from one tank to the next. My elevation will vary 5500 feet from where I leave my house to where we end up and air temps can vary 40 to 50 degrees throughout the season. With avgas I dont need to rejet all the time like I was with other fuels. Probably the most inconsistent jetting was blending vp110 and 91 pump to get my desired 100-102 octane. I found out the hard way on my turbo to get my octane numbers where they wont deto I needed an extra gallon of race fuel in the mix. I melted a piston from deto with a 50/50 mix of race/pump. For the motor to live on what avgas will do straight, I ended up 3 1/2 gallons of race and 1 1/2 gallons of pump. I decided it was easier and had better results with avgas. Anyway thats just my experience... By the way welcome back!

 

Also to the planes run low compression theory. My sled runs a 12:1 compression head and at 12 pounds of boost you end up with a lot of compression. Another old wives tale of avgas is its designed for engines that are low consistent rpm. Its just that, only a wives tale... I say try some different fuels and blends. See what works best for YOU and stick with it once you've got it tuned... :ride:

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Grand Master

Swappa

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New piston, 178main jet, Scotts damper and 14/49 gearing worked awesome during wide-open offroad racing over the weekend. The higher-speeds and better traction meant I was on the gas more and carrying momentum and therefore had no trouble with the herky jerky YZ 2-stroke power.

 

The stiff forks and overly active shock worked way better than I ever expected. The nose-high geometry meant that the bike was super-stable at 50-85 mph. Every time I applied the gas, the back would squat and track really well.

 

Too bad I felt so sick in the stomach during and after the race. Still trying to figure out why these health issues keep coming up.

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Grand Master

Swappa

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I attached a couple of photos from the race held last weekend (Credit M. Kariya) It is the District 37 Big 6 West Coast Grand Prix series.

The pictures dont show the YZ too well, unfotunately. Feel free to ask any setup questions.

 

 

I'm Looking fwd to JBC Glen Helen 24hour tomorrow. Our team won Vet 30+ last year on a pair of YZs so hopefully we can back it up with another win!

10658908_10202978847695720_9099330172897208935_o.jpg

10476996_10202978655450914_2842800233207793076_o.jpg

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Grand Master

Speed-Freek

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I attached a couple of photos from the race held last weekend (Credit M. Kariya) It is the District 37 Big 6 West Coast Grand Prix series.

The pictures dont show the YZ too well, unfotunately. Feel free to ask any setup questions.

 

 

I'm Looking fwd to JBC Glen Helen 24hour tomorrow. Our team won Vet 30+ last year on a pair of YZs so hopefully we can back it up with another win!

We should ride sometime, I race D37 as well, but mostly Desert races, not a ton of GPs. I didnt go to the Ridgecrest race...

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