First time to the dunes now for more power

[80'427]

I went to little sahara in OK this weekend for sandfest. It was awsome. Riding in the sand is 100 times cooler than I expected. The only problem is it isn't quick/fast enough. I dynoed it while I was there and on the dyno it put out 31 hp. That is with a FMF fatty w/ spark arester, and a K&N. I am thinking the engine is a little tired and may need some freshing since it should be closer to 39. If I pull the jug and add some ccs and have some porting done how much will I gain? Who should I have port it? How big will still be releable and easy on parts? How much $$$? While I was there nearly every banshee I saw was on its side getting worked on. I don't want this. I just want to shut up a few predator and 450r riders.

[Troll 2]

Looks like you could gain alot. Heres a couple of usefull links............... :D
http://www.macdizzy.com/trx_dyno.htm
http://www.macdizzy.com/sixtynine.htm
Good luck

[Dammit!]

Bigger carb, rad valve or v-force reeds, a good porting job, fresh bore/piston kit. With all that and making sure it's all tuned right you should notice a pretty big difference. Might want to make sure your clutch is up to snuff too. All that extra power won't mean much if you're not getting it to the rear wheels.

[firefirefire90]

get wiseco piston/rings..new reeds and porting. Oh yeah shave the head for wicked compression. 31 seems a lil low.

[Dammit!]

I wouldn't blindly recommend shaving the head for more compression. It's not quite that simple. If you increase the compression you increase your octane requirement. It will run hotter and you might find your stock ignition not strong enough anymore. I'm not saying don't do it, I'm just saying do a little research and know what you're getting into first. ;)

[80'427]

I would agree that 31 is low. It starts and runs great but I think it may getting a little worn. I have ported some sbc heads but I am a bit hessatant about first time porting of 2 stroke cylinders. Does mcdizzy do porting or is it just a guide? How much can I increse the compression and still use 92? I do have boysen reeds (or so I was told when I bought it). I was hoping for 45ish.

[80'427]

It was getting hot just the way it is. maybe that is 90+ degree day in the sand. It has the jetting dead on. Maybe I need the flush the rad and the engine coolent though.

[Dammit!]

The 39hp stock figure is at the crank. You'll lose a few hp at the rear wheel in comparison. Edit: could be a little more or even less depending on elevation and conditions.

92 octane is borderline for even a stock motor at the dunes (in my opinion anyway). If you really want to try it, just get a head gasket for a CR250 and see how it goes. They're quite a bit thinner than the ATC gasket (single layer versus triple layer). If you do that AND shave the head, count on using race fuel or at least a mix of 92 and race fuel.

[honda200]

take your slug out, inspect it, if there are no scores, run a hone through it, and get it nice and polished up, add a wiesco piston kit, port the motor. You said you have a FMF fatty with spark arrestor, have you concider changing the spark arrestor to a silencer? changing your sprockets will help in top end power, or bottom end, depending on how you change them.

Curtis

[firefirefire90]

think an 81 stock motor could handle a CR gasket, with super unleaded and a shaved head?I mean would that get super hot, seeing the motor is of course air cooled. I mean does race gas help with the heat? With ignition.. i duno. Would CR ignition be any better?

[MTS]

www.esr250.com

380 that sucker!!!!, ESR dose good port work from what i have herd and good things about there ATC-5 pipe...i would call em up.

[RedRider_AK]

Did you re-jet the carb after you stuck the FMF pipe and K&N Filter on it?

[RedRider_AK]

Oops, sorry! You mentioned jetting in one of your replies! Whoops!

[80'427]

it is actually jetted stock but the dyno showed a perfect fuel map and my plug always looks good.

[RedRider_AK]

it is actually jetted stock but the dyno showed a perfect fuel map and my plug always looks good.

Hmm... I would think that either it's off, or you just wasted a bunch of money on a pipe and filter, because if your machine is still properly jetted, after putting a high-airflow filter and a free-er flowing pipe on it, that means that it didn't increase the airflow through the engine, meaning you have stock power, still. Either way it sucks to have 31 hp...I mean, my 4-stroke Rancher prolly puts out that much...

[80'427]

I got the pipe used so I don't feel so bad maybe it is just that wore out that it is getting close to stock. The pipe helped alot esp w/o the airbox lid (before the K&n) As far as I know it is stock and never been apart. pretty good for a 85.

[RedRider_AK]

I still think there's something wrong. I mean, you CAN'T maintain stock jetting with a K&N filter, you just can't.

[Dammit!]

I still think there's something wrong. I mean, you CAN'T maintain stock jetting with a K&N filter, you just can't.

Yes you can. Jetting is more than the sum of your parts. Everything from altitude to atmospheric conditions effects it. You can take a bone stock 250R with stock jetting and take it to different parts of the country and at different times of year and that stock jetting at times will be either too rich or too lean by varying amounts and at other times it will be perfect. Odds are he was a little too rich prior to adding the pipe and filter, even if it was stock jetting. Check it again in the middle of the winter and it will be different. Having the airbox lid on or off makes a big difference too. That K&N filter isn't allowing nearly as much air to pass as it's capable of if the airbox lid is still on.

[OldSchoolin86]

Hmm... I would think that either it's off, or you just wasted a bunch of money on a pipe and filter, because if your machine is still properly jetted, after putting a high-airflow filter and a free-er flowing pipe on it, that means that it didn't increase the airflow through the engine, meaning you have stock power, still. Either way it sucks to have 31 hp...I mean, my 4-stroke Rancher prolly puts out that much...
Great comment. Did you ever think that maybe his mix was on the rich side before he piped it? Also I guess you know every last detail about his machine including the elevation that he was running at. :rolleyes:

EDIT: Opps, I see I'm 7hrs late for for this one.

[sandrooster]

I recommend a compression test before changing any settings or head gaskets. Just remember 175 to 200 psi indicates good to great condition topend. Anything lower than 175, I would rebuild topend.

[Blown 331]

If stock is 39 at the crank I'd say that should be just under 34 at the wheels, that's stock so I would agree something is up. How does it compare to other 250R's? Drag race any?
Of course I see the same thing with cars. Most people get a few mods and expect to see a bunch more power than what they dyno.

[slothminx]

You also gotta remember that when honda got there HP readings they were done in optimum conditions, this means humidity, air pressure the works. So i would run a compression test if you within spec then its normal only a bit under the book.

Will

[80'427]

Well, I live at 1310 ft above sea level. The oil mix I am currently using is 32 to 1 klotz racing 50. After adding the pipe but before removing the air box lid it would foul plugs. After removing the lid the plugs were a dark brown now the light tan that is should be. I will keep an eye on the plugs. I know how important proper jetting is. I was more looking for a little direction and insight about acheving a little more HP out of the ol 250R. Does anyone have a cylinder porter they recommend? Is there a set of reeds that are head and shoulders better or is like the chevy vs ford stuff. The plan really is to open it this winter, add rings or piston and rings if a bore/hone is required. Have the jug ported. Inspect reeds and related parts. I have building V8s since forever but I am a bit scared of wipping out the old grinder and going to town on a jug. Back when I was in plant maintenance they used to say hit the poor performers that give you the most gain. Thats what I am look for the areas that will give me a significant gain if I remine them. I don't want to swat at gnats when the buzzards are carrying me away. And what about the over heating? Detonation? Just the excessive load of the sand?

[Troll 2]

You'll need to have your jug pro. ported. Reading these five pages helps http://www.macdizzy.com/cyl_primer.htm. There site is great for info http://www.macdizzy.com/2stroke.htm. So is this http://www.ericgorr.com/twostktech/twostroketech.html. Good luck............ :D

[OldSchoolin86]

Well, I live at 1310 ft above sea level. The oil mix I am currently using is 32 to 1 klotz racing 50. After adding the pipe but before removing the air box lid it would foul plugs. After removing the lid the plugs were a dark brown now the light tan that is should be. I will keep an eye on the plugs. I know how important proper jetting is. I was more looking for a little direction and insight about acheving a little more HP out of the ol 250R. Does anyone have a cylinder porter they recommend? Is there a set of reeds that are head and shoulders better or is like the chevy vs ford stuff. The plan really is to open it this winter, add rings or piston and rings if a bore/hone is required. Have the jug ported. Inspect reeds and related parts. I have building V8s since forever but I am a bit scared of wipping out the old grinder and going to town on a jug. Back when I was in plant maintenance they used to say hit the poor performers that give you the most gain. Thats what I am look for the areas that will give me a significant gain if I remine them. I don't want to swat at gnats when the buzzards are carrying me away. And what about the over heating? Detonation? Just the excessive load of the sand?
32:1 for Klotz 50 is a little thick. You should be mixing that at 50:1.

[Troll 2]

Heres some ggod info http://www.tsrsoftware.com/.................. :naughty:

[80'427]

I agree most people add a mod to there rigs and expect the world from it but it did run better. Hell now it will fry the knobbies on pavment, it would just die before. I let my buddy ride it and he agrees it runs better with the pipe. I know the oil is mixed a bit thick next time I will go 50 to 1, but do you think it will make a 4-5 hp difference?. Didn't run any 250rs but the predators were eatting my lunch. I am having trouble on the launch 1st wants to wheele and 2nd bogs for 20ft then is gone. I can do well when wound out but the hole hot sucks unless I need to do a 2nd gear dump at 8 grand. I am a drag racer from way back but maybe I just can't drive this yet. I also had 2 other guys race it and they also thought it had a poor hole shot. I will do a compression test just need a gauge that will fit.

[MTS]

http://www.saberracing.com/

You could always go with that, its going on my 250r when i get a 250r and money...haha!