Plug reading advice needed

Hi,

I'm trying to fit a FCR37 to a DRZ400.  The fit is completed and I'm trying to tune it.  Recommended setup on different forum is #40 pilot #160 main and EMN needle 3rd clip.

 

#40 was not enought, engine temperature rise quickly on idle and rev stay high after throttle bliping.  Now pilot is #42 and 2 turn on pilot screw.

 

During my tuning, I also try a 162 main and bike feel rich so I get down to 160

 

Needle clip was moved to 2nd to help with bog.

 

Yesterday I made a test ride and the snap was ok and power too.  The only thing is in last gear, near 8200RPM and WOT, the engine wont pull anymore.  I red somewere it could be a indication of rich condition so I change the main jet to 158 and try it again.  I warm the bike with a little run and put it WOT in last gear for few seconds (5-7), hit the kill switch and pull the clutch.  I remove the plug and I have a light gray one side black on other one...

IMG_3244.JPG

 

 

I put a brand new one in the engine, riding few minutes trying to keep throttle between 1/4 to 3/4, hit the kill switch, pull the clutch and remove the plug.  I only a deposit on one side of the plug and this side is gray...near the electrode.

 

So I put back my needle to 3rd clip, still with #158 main and it run fine.

 

Any advice??

 

 

 

 

160 sounds like a good starting point for a 39mm, the 37 should require a smaller jet as the signal will be stronger.

When the bike "won't pull anymore". That's an Indication It's lean. when It's rich it will "splatter", run rough.

 

Doing a plug test with a new plug Isn't Ideal. IMO, a plug test is BS anyway, just sayin.

Thanks for reply!

 

Currently I'll stick with #160 and 3rd clip.  I'll tink it's the safest setup for now.  But #158 is probable the good one.

 

How much Km should I run the bike before checking the plug??

There is no way to read a plug using pump gas.

 

It has  too many additives in it to keep it fresh and low CO2, to make reading useful.

It will always come out looking lean, even if it's slightly rich.

 

Only and Air Fuel meter is practical.....or racing gas and a box of new plugs.....

 

Besides, you don't read the tip of the plug, you look down inside at the bottom of the porcelin and read that for Fuel Air mixture.

 

Reading the top is about heat range, gap, etc.

 

...but your plug looks fine.

 

Remember, the FCR conversion is NOT about making the bike a bunch faster or lots more horsepower. 

 

It's about consistent throttle response and partial throttle control, which the CV carb did very poorly.

There is no way to read a plug using pump gas.

 

It has  too many additives in it to keep it fresh and low CO2, to make reading useful.

It will always come out looking lean, even if it's slightly rich.

 

Only and Air Fuel meter is practical.....or racing gas and a box of new plugs.....

 

Besides, you don't read the tip of the plug, you look down inside at the bottom of the porcelin and read that for Fuel Air mixture.

 

Reading the top is about heat range, gap, etc.

 

...but your plug looks fine.

 

Remember, the FCR conversion is NOT about making the bike a bunch faster or lots more horsepower. 

 

It's about consistent throttle response and partial throttle control, which the CV carb did very poorly.

 

The idea of FCR isn't to get more power but get a better SNAP...  I have chance to try it this week-end and it's really better!  

 

If I can't read plug with pump gas, where should I get my gas to check plug?

 

Maybe I will put some money in a AFR meter, weld a bung on exaust and take reading...more costly, more precise but less time comsuming...

The idea of FCR isn't to get more power but get a better SNAP...  I have chance to try it this week-end and it's really better!  

 

If I can't read plug with pump gas, where should I get my gas to check plug?

 

Maybe I will put some money in a AFR meter, weld a bung on exaust and take reading...more costly, more precise but less time comsuming...

 

I would just copy another DRZ'ers jetting that is having good results, and go by the seat of your pants. 

If you think there is more to be had after that, get the AFMeter.

 

Reading plugs can be frustrating as hell.....

 

http://www.braigasen.com/howtoread.htm

The idea of FCR isn't to get more power but get a better SNAP...  I have chance to try it this week-end and it's really better!  

 

If I can't read plug with pump gas, where should I get my gas to check plug?

 

Maybe I will put some money in a AFR meter, weld a bung on exaust and take reading...more costly, more precise but less time comsuming...

 

Just use your feel and your ears. "It's not rocket science". Plug tests are BS.

Edited by AddictedToBling

Also, depending on the gearing your bike may not have enough hp to pull your top gear to redline.

I would just copy another DRZ'ers jetting that is having good results, and go by the seat of your pants. 

If you think there is more to be had after that, get the AFMeter.

 

Reading plugs can be frustrating as hell.....

 

http://www.braigasen.com/howtoread.htm

 

Yes it is...frustating

 

I just want to be sure the bike isn't too lean, I dont want bad surprise...with all the try I do ans the feeling I have, I thing I'm on the rich side.  I'll try to confirm it with plug but ...it's not easy!!! 

 

Your link is a great one, all infos I've found in smalls pieces around the web are in one place.  Great Link

Also, depending on the gearing your bike may not have enough hp to pull your top gear to redline.

 

I've got good acceleration up to a point and then  nothing...It feel like a rev limiter.  I reduce front sprocket size to get more torque on the wheel...not sure it's that

Just use your feel and your ears. "It's not rocket science". Plug tests are BS.

 

Up to now, I get better result with my feeling than with plug reading for sure!!

 

How do they do in garage to tune a bike in 1-2 hours?? (<- without dyno and AFR gage)  As I understand,  It's small change, one at time base on feeling during ride... They tune pilot circuit , and hope the other one is ok?

It's not a two stroke, so if it's a little lean, it's not going to sieze or blow up.

Lean feels like a kill button and rich feels like it's drowning.

 

The stock DRZ head and cam are extremely low performance.

 

Having said that, it takes about  $3k to make a really good DRZ motor.

 

You are better off starting with a WR450 or a 450X and plating it....

Edited by KRANNIE

It's not a two stroke, so if it's a little lean, it's not going to sieze or blow up.

Lean feels like a kill button and rich feels like it's drowning.

 

The stock DRZ head and cam are extremely low performance.

 

Having said that, it takes about  $3k to make a really good DRZ motor.

 

 

You are better off starting with a WR450 or a 450X and plating it....

 

I sold my WR450 to buy a DRZ400 because  here in Quebec we can't plate a WR...

 

My WR miss me....

After few hour of run, I remove the plug and cut it to see the base of porcelain.  Here is the picture 

IMG_3251.JPG

 

 

Some say to look at the base of porcelain for full throttle jetting.  In my case, it look I'm right on target!

looks perfect....but just get a lighted loop instead of destroying a perfectly good plug!

looks perfect....but just get a lighted loop instead of destroying a perfectly good plug!

 

I'll try it next time

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