Anyone have Problems with there 300ex getting hot and running bad?

[rebelbuggy]

Okay So I have only rode my 300ex for like 3 days now, never hard only for a few miniutes or so at a time ( more like 15 minutes at a time or less)

well me and my buddy went to the pratice track todfay so i could learn a little about riding a track, my quard would doing good but then started seeming like it didnt have any power in 3rd gear.. 1st and 2nd gear fine..

Well i let her cool for a few and well it seemed better so I figured it was cause I keep letting it idle and taking pics of my buddy riding and stuff cause my battery is bad and had to be jumped off so i keep it running.. i figured all that time just sitting idering it made it hot... BUT...

I came home the 4 wheeler sat for like 4 hours I just went out messed around with it and started riding in my yard... All kinda power thoughout all the gears then after about 30 minutes it started not having any power again in 3rd....

I dont get it. 1st and 2nd all kinda power but when I go to 3rd and hit the gas it like bogs down and at the track today i was having to shift into 2nd and reving it really high then shifing to 3rd to have any power. going level or slight hill. down hill it was doing fine....


Now maybe a couple of things... I didnt re jet it after the new piston .

I have a old spark plug in it ( my buddy said to buy a cold plug for it)

I have my air box lid still on ( maybe I should remove it and try)


But even with these maybes why would it run great untill it heated up? has anyone ever tested what there motors ran at?

I have a handheld temp gun (cause I fly rc planes and run rc trucks )

I just done the temp at my head and it was 370 right at the exhust pipe and about 340 the hottest anywhere else..

not sure there is a normal or not..


Any tips would be nice

thanks

[bradley300]

that sounds awful hot. is the piston a stocker, or is it a high compression? it sounds to me like you might be running a little lean. also, i would use a stock sparkplug

[rebelbuggy]

Originally posted by bradley300
that sounds awful hot. is the piston a stocker, or is it a high compression? it sounds to me like you might be running a little lean. also, i would use a stock sparkplug

No, its a 11:1 Comperson Wisco, I just done a rebuild on the bike. I had it bore over .40......
what would make it lean?

[300ex_#387]

Originally posted by rebelbuggy
No, its a 11:1 Comperson Wisco, I just done a rebuild on the bike. I had it bore over .40......
what would make it lean?

Your running a higher compression piston, and a bigger bore. Your going to want to put a bigger jet in it.

[00tn300ex]

had the same problem with mine,the only solution i found was putting an oil cooler on it.The 300's are fine stock not running a cooler,but ne major engine mods and u better put one on it.

[00tn300ex]

1 more thing make sure your oil filter is installed correct,someone had installed mine backwards and it was seizing the piston from not getting any oil

[rebelbuggy]

Originally posted by 300ex_#387
Your running a higher compression piston, and a bigger bore. Your going to want to put a bigger jet in it.

but why would it run fine untill it got warm? or not having the right jet making it get hot?

[rebelbuggy]

Originally posted by 00tn300ex
had the same problem with mine,the only solution i found was putting an oil cooler on it.The 300's are fine stock not running a cooler,but ne major engine mods and u better put one on it.

Really! so where did you find one? u use one for a 400? or....
Also How can you install a filter backwards, the rubber part goes on the spring inside tha the flat part is to the front..Its in right I changed it a couple of times now breaking in the engine.

[00tn300ex]

i went to the parts store and got a small transmission cooler and tapped in to the head feed line.do a search on this site thats how i figured it out

[rebelbuggy]

Originally posted by 00tn300ex
i went to the parts store and got a small transmission cooler and tapped in to the head feed line.do a search on this site thats how i figured it out

oh yeah, alright.
my buddy said to get a colder plug said he had to get one for his and also checking the air mixture screw

[00tn300ex]

the filter should go in the with rubber oring side (the side with the hole in it) towards the filter cover.

[00tn300ex]

any one correct me if im wrong but thats the way i put mine in since someone had put it in backwards before,rebelbuggy if it is in backwards its gonna cost you a complete topend.

[rebelbuggy]

Originally posted by 00tn300ex
the filter should go in the with rubber oring side (the side with the hole in it) towards the filter cover.

Thanks for telling me............. I took the old one off and it was on backwards, I didnt know.. Crap.... I will turn it around tooo and see if anyhting changes

[00tn300ex]

the perfect way to check is to take one of the rocker covers of and see if it is shooting oil out,by the way if it was in backwards you will most likely be buying rockers,rockershafts,cam,piston,get it bored.it is a very common and very very expensive mistake.

[00tn300ex]

Thanks for telling me............. I took the old one off and it was on backwards, I didnt know.. Crap.... I will turn it around tooo and see if anyhting changes yeah if my mechanic havent told me i wouldve done the same thing,lol he told me what had happened to it before he even took it apart by just hearing it.

[rebelbuggy]

fliped that thing around and rode it maybe 20 minute..... Now the idle seems higher and well temps are down , its like 275 now at the pipe ... the hottest wa slike 303... thats better then what I said before. I think i will go get a colder plug tommorrrow and try that then maybe rejet also

[00tn300ex]

how long did you ride it like that.I would guess you saying it was lossing power was the pistio gaulling in the cylinder.You might be ok but id say it has caused some damage.Glad to be of help,just always hate giving someone bad news.

[rebelbuggy]

Originally posted by 00tn300ex
the perfect way to check is to take one of the rocker covers of and see if it is shooting oil out,by the way if it was in backwards you will most likely be buying rockers,rockershafts,cam,piston,get it bored.it is a very common and very very expensive mistake.

well something was getting oil cause when I first put it together i had oil coming out of the top oil line and had to fix that, I adjusted the valves yesterday and they had oil on them I oiled the whole inside of the head before i put the covers on it, maybe they just had oil in it from that...

I just bored it out 40 over with new piston and all..

[00tn300ex]

yeah we just got mine finished a few weeks ago 80 over ported and polished,mine was running way hot i didnt have a temp gun but after i had ridden maybe 10 minutes i couldnt even touch the dipstick to check the oil.The oil cooler dropped the temp dramatically.You should definatly put one on it.i think i had maybe 60 bucks in mine.if you need pics of the install i can give them to you and if you have an oreilly auto parts store in your town i can give you all the part numbers.

[rebelbuggy]

Originally posted by 00tn300ex
yeah we just got mine finished a few weeks ago 80 over ported and polished,mine was running way hot i didnt have a temp gun but after i had ridden maybe 10 minutes i couldnt even touch the dipstick to check the oil.The oil cooler dropped the temp dramatically.You should definatly put one on it.i think i had maybe 60 bucks in mine.if you need pics of the install i can give them to you and if you have an oreilly auto parts store in your town i can give you all the part numbers.

wow 80 over I didnt know you could go that high of a bore with a 300.
I might have to check into it.

[rebelbuggy]

Originally posted by 00tn300ex
how long did you ride it like that.I would guess you saying it was lossing power was the pistio gaulling in the cylinder.You might be ok but id say it has caused some damage.Glad to be of help,just always hate giving someone bad news.

I guess its posible for a engine to have lots of power but be running bad on the inside..

like i said it was fine untill it got warm and hit 3rd, I didnt ride it hardly any with it doing that tho so I PRAY and hope everything will be fine

[00tn300ex]

yeah maybe you didnt hurt anything from reading your other threads you said you dont ride hard or anything.mine would still run after someone put the filter in wrong.just smoked alot.is it making alot of noise in the topend?

[rebelbuggy]

Originally posted by 00tn300ex
yeah maybe you didnt hurt anything from reading your other threads you said you dont ride hard or anything.mine would still run after someone put the filter in wrong.just smoked alot.is it making alot of noise in the topend?

Just the rocker arms were ticking... it done that as soon as I crunk it up from the rebuild thought it was valves but when we adjusted them we found out there is play left and right on them so I need new ones...

i got this bike from one my friends and he got it from some dude down the road... I dont know anything about it besides it wouldnt run but my friend said it was a piston and stuff and would be about $200 to fix it so I got it and it didnt have any compression and we tore into it and seen the piston and cyclinder all messed up so got new one and had bore and everything.

it was smoking just a tiny bit today when it was getitng hot but like I said i shut her down and let her cool off when it done that

as long as it wasnt hot it was running great

[00tn300ex]

i bet the piston and cylinder where all gouged and scratched up.was the filter in backwards when you bought it.that is how i got mine.someone elses mistake.payed 500 and 2200 dollars later she finally runs again

[rebelbuggy]

Originally posted by 00tn300ex
i bet the piston and cylinder where all gouged and scratched up.was the filter in backwards when you bought it.that is how i got mine.someone elses mistake.payed 500 and 2200 dollars later she finally runs again

yeah thats what i ment, i didnt change it when i first got it.and the piston was all messed up and the cyclinder walls were stratched up but they didnt run it with hardly any oil in it...it didnt have none shoing on the dip stick when i first got it either

i just had it bore over and new piston and all... i let it run about 20 minutes changed the oil then put new filter in but not knowing better i put it in same way as it was when i got the 4 wheeler.. backwards..

I think it should be okay now that its the right way and all... like i said i didnt run it much when it over heated and all... only about 2 1/2 hours IF that on the new top end

[bwamos]

Originally posted by rebelbuggy
oh yeah, alright.
my buddy said to get a colder plug said he had to get one for his and also checking the air mixture screw

FYI.. colder plug makes your engine hotter. Colder plug = colder tip = transfers more heat to the head to keep it cool.

[rebelbuggy]

Originally posted by bwamos
FYI.. colder plug makes your engine hotter. Colder plug = colder tip = transfers more heat to the head to keep it cool.

really, humm thats not what he said he said it make it run coolor.. i dont know

[bwamos]

A cold plug keeps the "tip" of the plug cooler in order to reduce the chance of detonation. Only way to keep the tip cooler is to transfer the heat. Ant that heat is transfered to the head.

A hotter plug keeps the tip hotter. A hotter plug will keep the engine a tad cooler due to less heat transfer, but is much more prone to detonation.

[2muchquad]

Only way to keep the tip cooler is to transfer the heat. Ant that heat is transfered to the head.

WTF:confused: your kidding right?

[00tn300ex]

I really dont know that much about the sparkplugs changing the heat of the engine much.From what ive seen bwamos knows his 300's well so I would say he is right.He can back me up on it but i would say the sperkplug would have little affect on the heat of the engine.

[rebelbuggy]

Originally posted by 00tn300ex
I really dont know that much about the sparkplugs changing the heat of the engine much.From what ive seen bwamos knows his 300's well so I would say he is right.He can back me up on it but i would say the sperkplug would have little affect on the heat of the engine.

I dont know for myself but my buddy said he was told by the honda dealership that a colder plug would help it not denenate and would let the engine rn cooler he said his seems to be running cooler now... but i dont really know.

[00tn300ex]

does ngk even make a colder plug?

[00tn300ex]

i looked on ngk website and they do make a D9EA.None of the stores around here keep them.Thats why i didnt know

[rebelbuggy]

Originally posted by 00tn300ex
does ngk even make a colder plug?

I dont know he said its either ngk or honda..

[rebelbuggy]

Originally posted by 00tn300ex
i looked on ngk website and they do make a D9EA.None of the stores around here keep them.Thats why i didnt know

Oh you posted while I was.... yeah. well local advance only has stock ones have to go to honda place to get anything else.

[00tn300ex]

just remember NGk is opposite of most plugs.the lower the number the hotter the plug.

[N300exJ]

NGK makes a plug that is one range hotter and one range colder than the stock plug. I know i have them all for my 300ex.