cr 80 running hot

[brentoncole]

hey had a few threads a while back and since then my bike is alot better but still has issues

* lately my bike has been running about 100+ degrees hotter than it was so now like 350 degrees on idle

*it has ate about 2 spark plugs(literally) i might put up a pic if its interesting to u guys

* it will not idle with the choke off so the jetting is probly wrong

so let me know what you think i am running premium 32:1 and i am using NGK spark plugs out of my dads truck(are 2 stroke plugs special), also my bottom head gasket is high comp and i have run about 5 hours since the new gasket so im not sure if it needs higher octane

 

[Matt90GT]

First off is there water in the radiator?

Second, go back to a stock NGK plug for the bike. BR9ES or BR10ES

Third, you said what your major problem is - will not idle without choke. you are running it super lean because the pilot jet/circuit is plugged up. Go through the carb and clean it. then inspect the reeds and intake boot for cracks and air leaks.

 

[ellandoh]

you might want to post a pic of that plug so someone can let you know if the jug has to come off. the crown of your piston may look like those plugs, and ready to burn a hole in it. then your in for real fun

 

[whenfoxforks-ruled]

Make sure the head to cylinder seal is good. The little red rocket is famous for a leaking head gasket seal. Help it run cooler, and bump the oil ratio up to 25:1. I sure hope you do not have 1 of my sons old race bikes! Vintage Bob

 

[Patman]

What are you using in the cooling system? If you have used tap water you for sure will have scale buildup which has a big impact on the ability of the engine to stay cool. Once you actually get it jetted properly and are using the correct sparkplug, clean the cooling system completly and run only distilled water with a bit of Redline Water Wetter. An oversized radiator from might not be a bad idea if you still have issues but not as a band-aid!!! If you decide you need a new stock radiator let me know I have one sitting on the shelf.

 

[brentoncole]

well my bike is air cooled and my carb is clean and and my air boot is crack free and my reeds appear fine but is there a difference between 2 and 4 stroke plugs, and where can i get diff jets heres a pic of my bike and then the cracked plug it like ate alot of the metal and then exploded the ceramic but dont worry it was in one piece when i took it out it just fell apart afterwards

 

[Patman]

Air cooled? That would make it even more critical to have the correct plug, jetting and extra oil in the premix.

 

[Matt90GT]

make sure you are moving to since it is air cooled

Also how did you check for air leaks? just looking at it is not going to cut it.

 

[brentoncole]

how do i check for leaks and what does the choke even do if there is no butterfly valve? it rides fine with the choke off it just wont idle or run below like 1k is it possible that it is running too rich since i have a 90's carb on an old 80's motor 79cc vs 83cc

 

[whenfoxforks-ruled]

Where did the rest of the ground strap go? Kinda looks melted off? I sure hope you post some pics of the top end. Running hot, a lean condition from,,,,? Vintage Bob

 

[Patman]

It will only do it for a short while longer Bob. ("it" = run)

 

[brentoncole]

i actually discovered the plug when i took the head off and it looked fine in there no scratches or chips and the ports looked fine but... then i looked at the head and saw the plug lol... okay i just did a couple min run and was at wot all the way back to my house and then hit the kill switch at wot my plug was pretty white so how do i richen it up i and im pretty sure i have no leaks and which is leaner choke on or off
P.S. my plug before this run was a real light brown

 

[ellandoh]

do you have the proper plugs yet, ?

 

[brentoncole]

yes i just bought a ngk br9es and went thru proper plug reading procedure looks on the lighter end of the spectrom

 

[Patman]

So why is it important to you for the bike to sit and idle with the choke on or off? Getting the bike to run cleanly through the RPM range and not melt down should be your realy goal.

The coloration on the plug could very well be from the addatives in the gasoline and not a real indicator so know what you are looking at. Personally I prefer my bikes to be a touch rich. The easiest place to start might be to unscrew the cap and raise the needle a position, maybe two and see what that does for ya'.

 

[brentoncole]

ya my carb is way weird i just took the slide out and there is only one notch and it is made by tk of japan and i looked it up and they make like chainsaw and lawn mower carbs but i couldnt find a company site or motorcycle carbs from them

 

[helio lucas]

tk makes some carbs for street bikes. i cannot recall any bike with that carb, even the brand, but i am pretty sure i saw it more than a dozen times.

wait, wait, my yamaha xt 600 have it. i remember now.

 

[brentoncole]

well i just ordered the slide and cap off ebay for the "original factory carb" looks like its in terrible shape though ill cross my fingers and hope it works maybe my bike will have more performance with the carb it is supposed to have

 

[Patman]

Wrong plug, wrong carb, bronken plugs and you are wondering why it's having problems? The carb thing was sort of a big deal to mention. Any other little secrets?

 

[whenfoxforks-ruled]

And all of the issues, will make the bike run hotter. Vintage Bob

 

[brentoncole]

well i guess im living and learning and i thought i kinda mentioned it i assumed it was the carb off the 1999 cr 80 frame but i think honda has always used keihn and no other secrets ill let you guys know what happens when i get the 1980 carb put back together

 

[brentoncole]

sup i got the original carb put back together and my bike runs awesom i checked the plug and it looks a little rich so im happy

 

[brentoncole]

okay guys should i start a new thread or resurrect this one

i put the old/new carb on my bike and it runs cooler and has more low end and topend power but it seems a way rich or sumthing because in low gears like 1st 2nd and alittle bit in 3rd and nuetral it cuts out at high rpm and sounds like "RUMMMM!-thoot-RUMMM!-toot-RUMMM!-toot" and then i back off the throttle and it sounds normal plus it has like black goo coming out the pipe i figure ill lower the needle a notch and see what that does also disconnecting the filter makes it cut out less

 

[brentoncole]

just a quick thought could a leaky fuel line make it cut out i noticed the carb is skinnier were the fuel line goes on and it was dripping some

 

[ellandoh]

theres one way to find out for sure