First ride - needs tuning

[6blueoval9]

Just finish your break in first, Sir

 

[Rusty_S85]

Oh I am. I have to wait till Monday to see if Bike Berry will warranty my chain tensioner if they do great. If not I have to buy a replacement for $25. I also bought the same air filter I had as well as a different style that if it fits I will use the other one its a oval K&N style filter. Aside from that I was going to ride the bike tomorrow before I went out of town but cant now with the problems I have. I also need to order a replacement fender bracket and drill out the fender bracket I have and install a heavier duty one.

 

[Rusty_S85]

Here is the video. Finally got it up. When I go full throttle you can hear a short period where the engine like just cuts out then takes off.

 

[6blueoval9]

That dead spot when you crack open the throttle is what is called a momentary lean condition.

At one point I could even hear what sounded like a lean misfire at part throttle.

I'd leave the 30 in it and play with needle..start full rich and work up.

If it clears up going richer on the needle you need a bigger pilot jet.

It wouldn't hurt to put the 75 main jet in and see how it works..if it 4 strokes or looses power then try the 72.5....if power picks up with the 75 then buy the next 2 jets going up...You want the motor to 4 stroke at full throttle so you know it's too rich then work down till it clears up.

 

[Street Ryderz]

Here is the video. Finally got it up. When I go full throttle you can hear a short period where the engine like just cuts out then takes off.

The dead spot is a momemtary lean condition because of two things 1.the engine just pulled in way to much air as the slide opened to full and the fuel flow has to catch up 2. just under the pipe coming on there is a slight loss of power because the exhaust return wave is off time.If you happen to crack the throttle right at that point the lag will be even more prononced. Your engine is very lean all around and when these engine are that lean you may never even see your real top end because the engine is strugling to make power with not enough a/f volume to achive proper cylinder fill efficaintcy and that's where the most usable and noticable power comes from.Fatten it up all around and run it some more like 6blueoval9 said you should be at least right at the point of 4 stroking at wot and have a slightly rough sounding rpm climb when you twist the throttle with no load not a fast clean rpm climb thats a bit to lean even for after your break in remeber that loaded will be even leaner.

 

[Rusty_S85]

well the needle was set on second clip from bottom I moved it up one clip cause I had a horrible stumble. Moving up one clip to lean the needle out improved the stumble for me. I guess I could take and move the clip back down to 2nd from bottom where it was originally and just live with the stumble till I get the engine broke in so I can do tuning on the carb. I would have to get the bike back together with air filter and drop the needle clip down one notch back where it was and see if it improves top end. I want to say top end was better but I moved it because there was a hesitation like it has now but moving it up one notch took most of the hesitation away and left me with what you see now. Might be a combination of running rich down load and lean up top.

But it sounds like I should go ahead and enrich the main jet to the 75 now and continue the break in if its better?

That also could be where my vibration is coming in at in the upper rpm range. I know a lean running automotive engine will run rough.

This is the alternative filter I ordered if it will fit I will be running this one instead.

https://www.treatland.tv/ProductDetails.asp?ProductCode=28mm-funny-n-crooked-filter

If not I will be using this one again.

https://www.treatland.tv/ProductDetails.asp?ProductCode=malossi-phbg-E8-filter-046199

I will just have to figure out a way to get the plastic to grip the metal neck of the carb so I don't lose another one.

I drove down 70% of the course I took yesterday today with no sign of my old filter. Not that id use it now. Just insane that someone would design a plastic filter that just doesn't have no ability to grip a metal carb neck.

 

[Rusty_S85]

Well I got all my stuff in today. Had a funny offset chrome K&N style filter to replace the plastic one that fell off. Sad to say that wont fit on my setup it hits the seat post. So I installed the new angled filter like I had that fell off. This one seems better than the last one maybe it was defective but this one I tightened it the same way and you cant even move it the neck flexes where as the old filter tightened up to the point of stripping out would spin.

I also fixed my broke rear fender mount, I drilled the two pop rivets out pulled the broken mount off and doubled up two 90* rear fender mounts and bolted them on. Fender is a lot stiffer now than it was before hopefully it doesn't break at the frame again.

I also pulled the carb off and pulled the #70 main jet out and installed my #75 main jet. I held both up to the light and to the eye they looked to be the same size but I figured its not hard to pull the carb back off just going to run it as I have no way of checking jet sizing without actually damaging the jet itself.

I also pulled my broke speedometer apart found out the tension spring is all twisted up but the odometer works fine. So I installed a new replacement speedometer in place but before I did this I took the new one apart and smeared with a piece of cable a good amount of Red N Tacky grease on all the plastic gears just as a precaution. They were quite noisy on my other speedometer hopefully this quiets them up.

 

[Philandra Chambliss]

Well I rode the bike today for a whopping 5 minutes before the motor got warm enough for the clutch cable to start sticking on me again. I finally had to push the bike with the engine engaged as fully pulled back on the clutch lever wasn't disengaging the engine think the arm slipped on the clutch cam again.

But I need some advise on tuning a Mikuni VM18 carb. Everything I find online is all scientific and measurement precise I just need to know how to tune it to get it better.

If I try to pedal start it the engine I guess tries to 4 stroke but wont run if you do get it running it stalls out pretty quick with a little throttle and releasing the clutch but that might be normal. Accelerating from a stand still you have to give a good amount of throttle and its fine but it does reach a point that it starts to feel like it lacks power and doesn't have a smooth pull.

I did get the bike up to about 15 mph not sure I want to go much more than that since I am still regaining my balance after not riding a bike in a good 20 years.

There backwards of Briggs if I'm correct unless I'm incorrect


You take the screws out inspect them and reset to base settings of no more then 2 1/2 turns for both if both sets of screws have no affect you need to reset.

One leans and one enriches...




Of I am wrong I'll self correct my self turn the screws all in until it gentally bottoms out then set them no more then 1/2 to 2 1/2 turns for both one sets the slide so it won't die if it's inside the car by the slide.

The other change air fuel mixture...


You should never have to go past 3rd clip notch from the bottom of the carb enrichner.

Do small blurbs as it warms up shouldn't hang idle or scream like a rock star having a throat blow out.

Soon as you lay off the throttle should snap back to idle quickly.

 

[Rusty_S85]

I ran the bike today first I tried out with the 75 jet. Went wide open throttle after rolling engine stalled out till I closed throttle a bit and the engine restarted. The clip was moved down to the 2nd notch before I rode it. I rose it to the 3rd notch from bottom and no difference still. So I pulled carb went down to the 67.5 jet was way worse bike wouldn't even pull on its own at half throttle. So I went and threw in the 72.5 main jet with the needle on the 3rd notch from bottom and it still has a hesitation when going wide open throttle but when I am moving down the road I noticed there were a few instances where going wide open throttle was no hesitation just took off and went. I don't want to move it down to the 2nd notch as that will enrich it and I am not sure if 1 notch would be too much for right now its good enough to finish my break in. Then I have to see might have to make changes if I decide to change up my fuel mixture.