G1 lean plug reading

[mikeasis]

After riding it around the block a few times this is the current plug reading, whiteish in color. This is a j17 engine and carb on a j10 chassis and j10 exhaust. VP Oil mixed at 50:1 with rec fuel. NGK plug BP6HS

I had a J10 carb on it first but it fouled out the plug a few times. Im not a carb guy by any means so any pointers appreciated.

[dezrcr822]

It does look lean. Here are a few shots of my plug. Note it is a NGK BP5HS and I see you are running a 6. Im running on my J17 a J10 carb and exhaust with jets from a Mokini chinese J10 knock off carb which are smaller than the J10 but bigger than the J17 jets which I think richens it up to tune for the carb and exhaust. I run Yamlube 2R premix mixed at 80:1 with 92 pump gas. I just really got my crate running and I am stoked as it runs great, pulls nice to redline and I surpassed my goal of 20mph with this setup.

[dezrcr822]

You may want to try just the J10 nozzle or J10 main jet and see where your at. A colder plug may help too ad you can always richen the mixture ratio up too. What is the octane rating of your fuel?

[CP241]

You're mixing 50:1. Try 100:1 and see if it improves. Most the guys I see on here seem to run between 100:1 and 128:1. The more oil in the gas, the more lean it will run. If you prefer 50:1 then up the jet in the carb a bit.

Also make sure the airbox is 100% completely sealed and there are no other airbox leaks. You could also step down to a slightly colder plug.

[griffo002]

What are the carb jet settings?....How many turns are you at?....like some run theirs at 1 turn others prefer 1 and a half....I think the book says 1 for old motors and 1 and half for new...In is rich ...out is lean.
Here is a link for tuning Mikuni carbs..

http://www.iwt.com.au/mikunicarb.htm

Griff

[mikeasis]

thank you for the replies. I belive the colder plug is the BP5HS and I couldn't find them anywhere at the time I bought this plug. I may have to find them on line and just order 2.

Im not sure on the carb settings I cleaned it up the and installed it and it seems to run well Im just not liking the look of the plug. Ill double check the intake piping today.

I belive the rec fuel is 89 octane but not %100 sure.

[griffo002]

The lower the number the hotter the plug apparently.....That one you show is the recommended plug from what I can tell....That is the middle one...You can use the one either side ...BP4HS or BP6HS.

[mikeasis]

Is this the pilot (mixture) screw? How should I proceed with adjustment, 1/4 turn at a time?

[mikeasis]

Originally Posted by griffo002

The lower the number the hotter the plug apparently.....That one you show is the recommended plug from what I can tell....That is the middle one...You can use the one either side ...BP4HS or BP6HS.

ok so the BP6 I have is a colder plug than the BP5? From what ive found the 5 is the correct plug for the 82 and the 6 for other years. Does that sound correct?

[dezrcr822]

Originally Posted by mikeasis

ok so the BP6 I have is a colder plug than the BP5? From what ive found the 5 is the correct plug for the 82 and the 6 for other years. Does that sound correct?

Yes NGK and some others have the lower number represent the hotter plug. 5 is correct for the 82 and 6 for the others gapped at 0.6-0.7 mm . I ordered a 4 pack online and keep them in my tool box in the bagwell along with a couple of 4's in case I may need a hotter one.