spark plugs
- Thread starter rcmackay3
- Start date
when u do trail riding you are in the lower rpm range and prone to foul plugs. You need a hotter plug to burn off the extra oil. a 9eg might do it. the heat range on plugs got 10eg cool up to like 7es very hot.
take a look at this reading guide, then maybe it will make sense. http://www.ngkntk.com.br/site_ingles/direct/p4.html
take a look at this reading guide, then maybe it will make sense. http://www.ngkntk.com.br/site_ingles/direct/p4.html
84cr125 said:
To each his own, changing your plugs heat range is masking a a jetting problem.
This makes a bit more sense;
DO NOT CHASE A JETTING PROBLEM BY CHANGING SPARKPLUG HEAT RANGES!!!
Here are a few jetting links;
http://www.all-offroad.com/DirtBike...rs/BGNov98.html
http://justkdx.dirtrider.net/carbtuning.html
http://www.keihin-us.com/tune.htm
http://www.keihin-us.com/am/_media/pdf/slide_valve.pdf
http://www.keihin-us.com/am/tuning/
http://www.maximausa.com/technical/...gsummer2001.pdf
http://www.powroll.com/tech_specs_jetting101.htm
Some Spark Plug Links;
http://www.strappe.com/plugs.html
http://www.dansmc.com/spark_plugs/s...gs_catalog.html
http://www.ngksparkplugs.com/techin...1000&country=US
http://www.ngksparkplugs.com/techin...1300&country=US
snb73 said:
Trail riding is not wrong jetting...... if he was to rejet for trail riding and then say drive down the road back home in 5th or 6th he will risk a seizure. If he keeps his current jetting which is good for high speeds but switch the plugh to a higher heat range he will be able to burn the extra oil at the low rpm, range.
rmc_olderthandirt
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- Apr 18, 2006
- 1,533
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84cr125 said:
The jetting is either right or its not, there shouldn't be any rejetting for higher speeds. It is the main jet's job to mix the proper fuel to air at higher RPMS. It is the idle jet that makes sure it is right at idle. It is the metering jet that gets it right for the transition between low and high RPMs.
An extended run at maximum RPM is asking for trouble, so I suppose if you are unable to control yourself that you might be better off to de-tune your bike so that it simply won't develop that power in the first place. But keep in mind that intentionally jetting your bike rich to avoid the high speed heating issues might make the bike exceptionaly hard to start.
Rod
Some bikes aren't built to putt around on trails all day. Rejetting or changing plugs to try to get the bike to run without fouling while putting around will cause it to run lean or hot and could result in a hole in the piston crown if the rider ever does open it up. Going from a 10 heat range to an 8 might be wise, but certainly don't go to a 7 or worse, a 6. Leaning it out to prevent fouling can have similar consequences.
I do not buy it,gm you surprise me again. Jetted properly is just that,baring mechanical issues the bike will not load up or seize under normal operation,simple. By the "figures"technology,all trials bikes must be 4 strokes,2 stroke race bikes are rode at 20,000 rpm and if you put 2 cycle oil in the trans,you do not have to put it in the tank! Who needs crank seals,the suits are screwing us out of unnecessary,expensive bs,ooh,ooh did you see the New even scarier now bolt on magic???? It will NEVER end! To any body that cares,read the posts and I hope the one is there about the groundstrap falling off the es plugs ran for extended periods in race bikes,and the powerband can be matched to suit your riding needs.Put the correct plug in the 85,rule out mechanical issues,jet it,,it is your sons bike afterall
I guess nobody ever complained about the jetting or the plug, it just led into a big argument about jetting and plugs. Throw a #10 or #9 plug in there and let your son ride it. If it fouls, then start asking questions. It's funny how everything becomes an argument on the internet.
Fox, I was saying that a CR85 is a motocross bike and not a trials bike. A trials bike can idle all day long without loading up or fouling a plug. The CR85 can't. Almost all trail riding conditions will keep the plug hot and clean. But, if the rider really putts around or does a lot of very technical single tracks, plug fouling can become an issue that is exagerated by the more aggressive tuning of a MX engine.
Fox, I was saying that a CR85 is a motocross bike and not a trials bike. A trials bike can idle all day long without loading up or fouling a plug. The CR85 can't. Almost all trail riding conditions will keep the plug hot and clean. But, if the rider really putts around or does a lot of very technical single tracks, plug fouling can become an issue that is exagerated by the more aggressive tuning of a MX engine.
Do not even think of checking the old plug to see if it is the proper heat range,it sounds like you need a hotter plug!WRONG ANSWER,if your old plug says you need to go hotter,ONLY THEN! AS I SAID BEFORE,rule out mechanical issues,Jet Your Bike,don't be afraid.84cr125 do you buy lottery tickets?
I trail ride, my jetting is pretty close to perfect for both trails and mx. There is a reason why there are different jets for different throttle positions. I use the stock heat range plug. I don't change for one environment or the other. I have absolutely no problems with fouling.
Jesus, where are all these people coming from? I've seen quite a few posts that have just absolutely stupid suggestions. If you don't know, don't answer. A few years ago this was a good board.
Jesus, where are all these people coming from? I've seen quite a few posts that have just absolutely stupid suggestions. If you don't know, don't answer. A few years ago this was a good board.
snb73 said:
You are making a blanket statement thats not 100%. You are correct that you should not try to fix jetting by changing heat ranges in plugs.
But in his case jetting isn't the issue. As an example YZ-85's have BR10EG listed as stock. I don't know anyone who runs them even in modified motors; they all run BR9EG's (as we do in our son's). The BR10EG is too cold a plug for anything but constant wide open throttle in an 85.
How do you think the manufacturers come up with a heat range for an particular bike anyway? Its not some "set in stone" number anymore than jetting is.
The plug listed as "standard" is based on the intended use the manufacturer see's the bike used for.
If a motocross bike, the manufacturer assumes lots of heavy load at large throttle openings (i.e. a lot of heat) and will generally specify a colder plug.
If you trail ride it; you aren't generating that amount of heat and in fact the plug may not be running hot enough to clean itself (even with spot on jetting) so going one step hotter is a good solution.
I often run a BR7ES in my YZ if I am just trail riding it.
Selecting the correct heat range plug for your needs falls right in there with selecting the correct jetting.
So while you are right that attempting to fix bad jetting by changing heat ranges is bad; its also perfectly acceptable to go up or down one heat range depending on how the bike is ridden.
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