Engine Builders! Tech queston for YA

A high compression piston is a inexpensive way to get a performance gain. As long as you buy from a reputal piston manufacturer you can't go wrong. The Hot Cams stage 2 cam works well on that bike also. It would be a good idea to update the valve springs if installing the cam. The Hinson components are great but I would not install them unless the stock stuff is worn.

Hey noob, get a blue power band and titanium muffler bearing.

Your best bet for performance and reliability is to contact RHC (Ron Hamp) at 1 (989) 463-1267

Order his ported head complete with ferrea valves, springs, his 187 grind cam and JE hc piston kit.

You will be blown away with the performance and people have been getting 100 hours out of this set up.

[quote="hidesintrees":352na48t]thanks but that sounds spendy, like 1500 spendy ehh? id do it it if i could though![/quote:352na48t]


[b:352na48t]im getting into racing [/b:352na48t]

I doubt you'll have an issue since your bike seems to be in very good condition, but.. The high compression piston will put a little bit more strain on your bottom end, so if it's on the verge of locking up, it will happen sooner than with a regular piston, but most likely you won't have this kind of issue.

Call this number: 414-467-6199


Talk to Jessie...


Ask him anything.

the crf's are a great platform... and we have some pretty inexpensive mods that will yield huge gains. you just have to do them in the right order.

that's my number above... and advice is free. just give me a shout.

Jessie is a friend
Yeah I know he's been a good friend of mine
But lately something’s changed, that ain't hard to define
Jessie's got himself a girl, and I wanna make her mine

My opinion and I build a lot of engines for locals here. If you're not an A rider or at least a fast B rider. Put it all back stock. The stock stuff lasts as long as anything and you know what you're getting. If you're not A or fast B you don't need any more than what you have. Just turn that rubber thingy on the right side of the handle bar harder while you're on the track.

[quote="Rallendude":35sxyle9]My opinion and I build a lot of engines for locals here. If you're not an A rider or at least a fast B rider. Put it all back stock. The stock stuff lasts as long as anything and you know what you're getting. If you're not A or fast B you don't need any more than what you have. Just turn that rubber thingy on the right side of the handle bar harder while you're on the track.[/quote:35sxyle9]
Most accurate post on MD in a long, long time.

[quote="hidesintrees":2temm0se] i usually mix 110 octane with premium to get 103ish.[/quote:2temm0se]
The math doesnt work like that.

[quote="hidesintrees":2v1hgrz0]ya im intermediate so im not saying i NEED more power im mostly looking for life span with the perks of more on top, i checked Williams and those valves sound pretty cool, i was origionally leaning towards wiseco because they say their pistons last longer but ive heard people say they come apart soo, has anyone used em to vouch for there performance?
in my mind valve springs and a good piston sounds like a good start providing my vavles are in good shape, i hope they are because i usually mix 110 octane with premium to get 103ish. thanks for all the input it helps ive already eliminated a few things that i figure i just dont need yet[/quote:2v1hgrz0]

An intermediate that's thinking about getting into racing? What's wrong with this picture......

MR

[quote="Racer92":klqq3zxd][quote="Rallendude":klqq3zxd]My opinion and I build a lot of engines for locals here. If you're not an A rider or at least a fast B rider. Put it all back stock. The stock stuff lasts as long as anything and you know what you're getting. If you're not A or fast B you don't need any more than what you have. Just turn that rubber thingy on the right side of the handle bar harder while you're on the track.[/quote:klqq3zxd]
Most accurate post on MD in a long, long time.[/quote:klqq3zxd]

X2.

[quote="hidesintrees":2ys071hi]ya im intermediate so im not saying i NEED more power im mostly looking for life span with the perks of more on top, i checked Williams and those valves sound pretty cool, i was origionally leaning towards wiseco because they say their pistons last longer but ive heard people say they come apart soo, has anyone used em to vouch for there performance?
in my mind valve springs and a good piston sounds like a good start providing my vavles are in good shape, i hope they are because i usually mix 110 octane with premium to get 103ish. thanks for all the input it helps ive already eliminated a few things that i figure i just dont need yet[/quote:2ys071hi]


I use Wiseco in some 2 stroke applications but prefer the JE or CP pistons for 4 strokes.

[quote="hidesintrees":1mb5am8l]so im freshening up my top end on my 05 crf250.
it probly has 50 some hours on it hasnt really been ridden too hard (i.e. raced for long periods of time) regular maintenance still looks newish, checked valves there still in spec n have never been out of. im getting into racing now but it is a bit smokey at start up now and im thinkin its time for some rings.
my thoughts/ options
i could go with oem
wiseco
high compression P.C. or MDK
piston but i do not know anything about these products, who believes in what here? oem obviously isnt terrible but to get a bit more power mid/up top whats the best deal? i was leaning towards PC or MDK and maybe some PC valve springs
i will check all of my oem parts for wear when i pull it apart and see just what needs replacing, also my bike has full Dr.D ss exhaust, powernow bladeS, Boyesen Quickshot, & Twin Air Pro filter with backfire screen removed (havent run it w/out screen yet, still waiting for filter) so itll probly respond to a hc piston more so then stock.
also id like to get some hinson components everyone says they dont wear and its completely worth it, agree? was think atleast the basket and inner hub
also i thought about the big gun ignition box, revs a little higher and changes power curve maybe? but will that jeopardise valve life
thanks[/quote:1mb5am8l]

If it smokes at startup, then your valve stem seals are going bye bye. If you're going to replace the valves or even just the springs, you should replace the valve stem seals when you do. Otherwise you'll do all the work you spoke of, and it'll still smoke at startup.

[quote="hidesintrees":1zjlic84]if you know what thatd be lets hear it. id like to know[/quote:1zjlic84]
When you start blending automotive pump gasoline with specially blended race gasoline, there is no telling what you will end up with regarding the specifications. You cant just 'sum' the advertised Octane ratings and divide by two. It doesnt work like that. Standard unleaded pump gas has a long list of specs it has to meet before it can be sold for automotive use. These specs require many, many additives in the gasoline. These additives collectively change the behavior of the gasoline and all of its physical specifications. Including but not limitied to the RVP, specific gravity and especially the distillation curve. Race gasoline, is blended to perform more favorably for a given application, and it likewise has additives blended into it. For instance here is the spec for Track-Tek TT-100UL.

[url=http://www.cpchem.com/enu/tds_unsecured/TT100_racing_fuel(1).pdf:1zjlic… TEK TT100[/url:1zjlic84]

The RVP, specific gravity, distillation curve and all the rest is published there and these race fuels will perform better because they arent encumbered with the long list of EPA specs to meet emission requirements.

Here is some good basic info on gasoline and how it is measured, and why some blends work better for different applications.

http://www.chevron.com/products/ourfuel ... mplete.pdf

Youd be better off running plain Premium pump gas or straight race gasoline before mixing it up and not have a clue what the end product is, IMHO. Further, when you mix with pump gas, you doubtless do away with much of the benefit of the race gas to begin with. 99.9% of the time, the octane rating is not a concern because OEM dirtbikes will operate fine on pump gas without detonating. The good part of race gas is the other specs and how the gasoline behaves when burned, and how much can indeed BE burned, plus it has a very consistent makeup batch-to-batch. Also, many of the 'octane boosters' are merely toluene or xylene, and this stuff changes the behavior of the flame front at ignition and has unpredictable results as well.

Heres some info for what its worth: http://www.kartweb.com/TechArt/Fuel/fuel_summary.htm

WWJD?

[quote="Racer92":2s13x2uc]Hey noob, get a blue power band and titanium muffler bearing.[/quote:2s13x2uc]
You missed the obvious Racer92, BUY A TWO STROKE!!! You will be much happier and faster! Just sayin' " title="Laughing">

All the thumper rider's saw this weekend was the back of this.. [img:srrqe8zt]http://i183.photobucket.com/albums/x176/RobbieO_2007/050000001198040.jp…]

[quote="hidesintrees":badlzrsu]racer 92- thanks for that info i had no idea..obviously. im kinda annoyed i never found that out i feel as if ive wasted money "blending" gases :l isnt it only really necessary to run high octane on compression over 12.1/13.1? ..so like a PC built motor[/quote:badlzrsu]
Im not a hydrocarbon chemist and Im can only read what is published and make decisions accordingly. I have studied the science of gasoline in great detail over the years and there is so much myth out there its not funny. But in my opinion you would do better to not mix gasolines - but I would love to find facts supporting the contrary. I did find a link once that showed a race fuel company that supported mixing fuels, read this and come to your own conclusions. They discuss a resulting octane rating, but dont get into the aromatics and how they would be affected - and to me [i:badlzrsu]that[/i:badlzrsu] is one of the most important factors regarding gasoline.

http://www.idavette.net/hib/fuel

Most companies that sell race fuels will tell you what compression range their fuels will work best with - so Id go by the stats that each respective company publishes. I do know that most OEMs build their engines to operate safely within the specs of Premium automotive gasoline and not detonate. Once you start altering compression, timing and other factors is when it would be wise to look at the various gasolines available and see which would suit your application.

Heres a bit more info for what its worth:

http://www.gwocgb.co.uk/documents/tgw_mc-fuel.pdf

sounds like your bike has all the mods you would need for the motor. clean it up and replace whats bad with factory stuff. buy the highest octain pump gas you can get localy (i think sunoco has 94).then go get your suspension done!!!!!

the trick is replacing the bad parts with better parts, performance, reliability without "paying" for performance when you're replacing anyhow.

In my opinion, there are three basic reasons to run race fuel. Just a little more FYI on race gasses.

1. Octane - If you are running a high compression engine, standard pump gas can detonate due to an insufficient octane rating. Some late model two-strokes suffer from this stock. The KX250 and the YZ250 come to mind. I know lots of people who have had good success running a 50/50 mix of C12 or 110 (both VP fuels) and 93 pump gas. To assume that the octane averages would be wrong. But the end result is that the detonation goes away and they end up with a fuel they've paid an average of $6 per gallon instead of $10 or $15 per gallon. Octane is nothing more than a fuel's resistance to detonate or burn. You ONLY want to run enough octane to prevent detonation. If you have a stock CRF50 and put C12 or U4 in it, it will not run as good as it would on 93 pump gas. The engine doesn't have enough compression to make a complete burn of the fuel. Of course, jetting comes to play here as well.

Oh, another point about octane. At least in the VP fuel the octane is usually listed as "motor octane". The pump is M+R/2, which is the average number of "motor" octane vs. "research" octane. This means that a 110 octane race gas would usually rate around 112 or 115 at the pump. The standard U4 octane of 92 is more like a 95 or 98 at the pump.

2. Quality - One major benefit to running race gas is that it is a lot closer to the same every time you fill up. Pump gas can vary greatly even if you buy it from the same station all the time. Fuel manufacturers change their chemistry for the seasons and that's what goes into your tank of you buy from the pump. Nothing wrong with that in most cases. Today's four-stroke engines are built to run on the average 93 octane pump gas. The don't need 100 or 110 octane ratings. You actually loose horsepower by running an octane rating that's too high for your engine. Also, most race fuels today, unless otherwise stated are leaded. Lead is good for race engines. It acts as a cooler or heat sink. The lead is drawn to the hot parts and helps lubricate and cool those parts. It also helps prevent detonation.

3. Horsepower - Today's race fuel manufacturers are doing lots of things to make more horsepower. If you want a simple quick (reversible) mod for a race bike pour in some leaded oxygenated race fuel. The U4 and U2 boast a 6% horsepower increase just by changing fuels, In most cases the jetting doesn't change much and you can go back to running pump gas after the races. There are other fuels like their MRX01 that are even more heavily oxygenated. I think it was benzene or butylene that the AMA found everyone was using a couple years ago and they gave the SX teams a pass. The fuel suppliers have a lot of neat tricks to get more hp from fuel and this is a relatively cheap mod trick.

Rebuild the bike stock and buy some running shoes and a gym membership. You'll be amazed at the performance gain.