[MikeBE]

Hello,

With the Covid-lockdown I bought a project bullet to keep myself busy in my shed. The bike was stranded in the middle of a poor attemt at a 'caféracer'. I took it apart and rebuild it as a minimalistic style bobber. The engine is a '06 AVL with TCI unit.  I've finished the bike last week. It also has custom wiring and is kick-start only.

It has a funnel with some mesh for an air intake and a few pipes with a db-killer bolted in for an exhaust muffler.



Right after I built the bike, to my own surprise started up after just a few kicks. I rode it straight to the gas station (1/2 - 1 mile), filled up the brand the new trials tank (with brand new petrol tap and filter, new petrol hose) with regular 95 octane.  Then took it for a 15 mile ride around town and stopped at my parents. Every time it started on the first kick and it rode perfectly (my first royal enfield, so hard to compare, but no real issues). After I start it usually idles a bit slow, so I hold in the clutch for a few seconds and after that it idle's just perfect.

But now, after those 15 miles, when I take it for a ride, it will be fine for 1-2 miles. But then it will loose power and stall while riding. I can pull in the clutch to stop it from stalling, but it does not fix it. It will then just stall a bit further again.

What could cause this? What would be the usually suspects?

Thanks,
kind regards, Michiel.

[Nitrowing]

First thing in my mind is fuel starvation.
Do you have a filter (maybe in your petrol tap) to clean?

[Bilgemaster]

First of all, that looks like a 350 Iron Cylinder Engine and not an AVL.

Secondly, that carb looks truly "Ghetto Fabulous" with those sepia-toned guano streaks or whatever that is down the sides. My hunch is the inside bits can't be much tidier than the outside ones. If you're having idling or other problems after warming up, that crusty-looking carb would be my primary suspect. It surely needs a good long soak and a thorough cleaning...maybe three. Got a buddy with a little ultrasonic parts cleaner? That might be best...or at least most likely to actually get it clean the first time.

Kind of a cute plucky-looking ride though. I see real potential.

[axman88]

Maybe a clogged tank vent?

If it's that, you'll be able to ride further with less gas in the tank, and loosening the cap will fix the issue.

[MikeBE]

Thanks for the feedback.
I was thinking a fuel issue as well, the fuel bowl not being replenished fast enough. It is a brand new fuel tank, tap and hose. Tonight I will have a look for that tank vent. Could I just leave the filler plug on a gap and give it a test ride? Not the safest but will determine if that is indeed the issue.

Perhaps the new fuel line is too narrow, it does go in a S-shape (up/down) so that might hinder the gas flowing to the carb. If leaving the filler plug open does not solve the issue, I will try to install the original hose.

Last measure would indeed be to give that carb a thorough cleaning, it could definatly use it. I didn't to it before because it was supposed to run fine, so why fix it?

[tooseevee]

Hello,

With the Covid-lockdown I bought a project bullet to keep myself busy in my shed. The bike was stranded in the middle of a poor attemt at a 'caféracer'. I took it apart and rebuild it as a minimalistic style bobber. The engine is a '06 AVL with TCI unit.  I've finished the bike last week. It also has custom wiring and is kick-start only.

It has a funnel with some mesh for an air intake and a few pipes with a db-killer bolted in for an exhaust muffler.

Right after I built the bike, to my own surprise started up after just a few kicks. I rode it straight to the gas station (1/2 - 1 mile), filled up the brand the new trials tank (with brand new petrol tap and filter, new petrol hose) with regular 95 octane.  Then took it for a 15 mile ride around town and stopped at my parents. Every time it started on the first kick and it rode perfectly (my first royal enfield, so hard to compare, but no real issues). After I start it usually idles a bit slow, so I hold in the clutch for a few seconds and after that it idle's just perfect.

But now, after those 15 miles, when I take it for a ride, it will be fine for 1-2 miles. But then it will loose power and stall while riding. I can pull in the clutch to stop it from stalling, but it does not fix it. It will then just stall a bit further again.

What could cause this? What would be the usually suspects?

Thanks,
kind regards, Michiel.

       I love your bike, I'd like to blast around my back field on it, but it would rip my old arms off 

       And you need to revise your belief that it's an AVL. I'm afraid it's not 

       Carry on and welcome. I love garage-built bikes 

[Adrian II]

I'd like to blast around my back field on it, but it would rip my old arms off

A stock 350 motor versus your Fireball 500 AVL? Don't think so, tooseevee! 

@ Mike,

check the breather in the fuel filler cap.

A.

[MikeBE]

Well, it IS lighter than stock 😂.

Anyway, I just came from work on my trusty GS and took the bullet for a test ride.

I opened up the filler cap as often as I could while riding (totally safe) and it still stalled on me.

When I felt it holding back I held in the clutch and put it in neutral and it still stalled.

I’m pretty sure it is not the breather, no way there could be a vacuum. But I would think there is something wrong with fuel delivery, but strange that it did not occur when I first rode it.

Perhaps the tank wasn’t completely clean and the filter on the Petrol tap is partly blocked. Will check when I have some time.
 
What should the inner diameter of the fuel hose be? I didn’t keep the original. This one is approx 5mm and was tight to get on, as it should I expect.

[tooseevee]

A stock 350 motor versus your Fireball 500 AVL? Don't think so, tooseevee! 

@ Mike,

check the breather in the fuel filler cap.

A.

      I didn't mean it powerwise. I meant it painwise. There's not a joint in my body that doesn't hurt because of 82 years with Ehler-s Danlos and scoliosis. My shoulders have been dislocated a thousand times since junior high school and now they fall out of joint by their own weight if I'm not careful. There is no collagen left between any of my bones anywhere and everything else made of collagen is also totally deteriorated.

       I've had pain my whole life pretty much from late grade school. I've just fought it all the way which has been both bad and good. I've done damage that whiners would never do; they just quit. I never have given in to it.

       I meant it painwise, not powerwise. This is also why I probably have the lowest mileage '08 AVL on the planet I have high mileage in mods and improvements and low mileage real ridingwise. 12 or 14 miles and I'm worried about dropping the bike or not being able to pull the clutch before I get back into my driveway and my shoulders, neck and back are screaming at me. I think I've put 14 miles on it this summer. And a new petcock 

[tooseevee]

Perhaps the tank wasn’t completely clean and the filter on the Petrol tap is partly blocked. Will check when I have some time.

           The gushing of the gas when you filled up could have stirred up a bunch of crap.

[Adrian II]

Most fuel hose for these is ¼" or 6mm I/D. You just need the holes in your fuel tap/hose etc to be bigger than your main jet.

If that's one of Hitchcocks' tanks, what fuel tap/petcock did you get with it? Some of the Indian ones aren't very free-flowing, you want a good one from a classic bike shop that deals with old British stuff. Tooseevee recently fitted a new petcock to his AVL500, have a read up on that.

Failing that try an OBSESSIVE carb clean, every last little jet and teeny passageway drilled into the carburetor body must be clear. I don't know what filtration the Mikarb has, if it's junk, fit an in-line fuel filter.

A.

[MikeBE]

Thanks for the suggestions.

Yesterday I took off the fuel hose, when I turned the tap open it was just a slow dripple of fuel at first. Only when I put the hose straight down it would run a bit faster. I took the petrol tap out of the tank, everything seemed perfectly clean. The tap came with the tank (https://accessories.hitchcocksmotorcycles.com/accessory-shop/Trials-Tanks-Alloy/22720) and is indeed indian made (Pelikan brand). It looks a bit like this one, except the filter body is metal and not plastic https://accessories.hitchcocksmotorcycles.com/accessory-shop/Large-Capacity-Petrol-Tank-1950s-Bullet/1370.

The bottom part of the tap is even, or perhaps even lower, than the fuel-intake of the carb. So the hose has to come up a bit to the carb. I made a new, shorter, fuel hose and added in a transparant fuel filter so I could see if fuel is getting to the carb. I can see fuel getting in the filter. When it stalled, it did not seem like the fuel-filter was empty. I could sometimes see the fuel filter (in the hose) getting emptier but then it refills. Although, this does not prove that the carb is getting fuel...

Perhaps cleaning the carb is the best next step, but haven't done that before.

[Adrian II]

Oh NO, why do they even supply those? Especially when they have these. Cost, I suppose.



https://accessories.hitchcocksmotorcycles.com/Amal-Carburettors/Petrol-Tap-Amal/3338

Or if you want a shiny chrome one, something like this, check that there's no stand pipe under the gauze filter.

https://www.ebay.co.uk/itm/Petrol-Tap-1-4-BSP-to-1-4-BSP-Lever-action-on-off-Chrome-plated/324256860503?hash=item4b7f370957:g:tlIAAOSwYdZfHhOB

Both of the above will need a ¼" BSP female hose tail fitting for the fuel pipe, you can get them straight or with a 90° angle.

There should be no major problems stripping the carb, just make sure you don't lose ANYTHING (that includes any little washers you find), and that EVERYTHING is replaced in exactly the right order, (note how many turns out the pilot air screw is and be sure to refit it with the same number of turns, usually around one and a half). Draw yourself a picture of the parts assembly sequence if it helps. You want to a able to blow through every little hole and jet, it might be worth having the carb body ultra-sonically cleaned.

A.

[MikeBE]

Thanks, I ordered a tap like that, two copper washers and a 90° brass fitting on amazon (for a wopping 17£, 3x the price from ebay but it is in stock and should be here by friday). Will probably try to clean the carb during weekend. I know it is not hard, but it is fiddly work and I'm not the most patient man. 

[Bilgemaster]

The attached PDF courtesy of our Forum hosts titled "MIKCARB NOTES - A4.pdf" may be of some help.