Boyesen - Dellorto Phbl

[gordeee]

Now that my bike is up and running again, I've a few parts here to fit on the bike. Throttle cable and the likes.

One of things I have is a new set of reeds, they're Boyesen #659.

Please can anyone tell me any alterations that may be necessary when fitting these reeds along with the Dellorto phbl 26 carburettor.

My Needle/Jet sizes at the moment are

Needle D36,clip on the third notch down

Pilot jet 35, Choke 60, Main 120

The mixture screw is 2 1/2 turns out and the Idle screw is about 4 1/2 turns out.

Any advice would be much appreciated.

Gordie

Edited September 12, 2010 by Gordeee

[copemech]

The Boyesen guidelines will tell you that the motor may run a bit on the rich side, if anything.. Typacally this is not that drastic, and not lot of change is needed on a trials bike. Adjust your fuel screw for best running, and if anything, drop the main jet a bit if it is lumpy on the top and will not clean out well.

Edited September 14, 2010 by copemech

[jse]

Now that my bike is up and running again, I've a few parts here to fit on the bike. Throttle cable and the likes.

One of things I have is a new set of reeds, they're Boyesen #659.

Please can anyone tell me any alterations that may be necessary when fitting these reeds along with the Dellorto phbl 26 carburettor.

My Needle/Jet sizes at the moment are

Needle D36,clip on the third notch down

Pilot jet 35, Choke 60, Main 120

The mixture screw is 2 1/2 turns out and the Idle screw is about 4 1/2 turns out.

Any advice would be much appreciated.

Gordie

Hi Gordie.

Here's a few tips that might help:

Before installing the Boyesen reeds, use a little 600 grit wet/dry sandpaper to very, very lightly radius the edges of the reeds (maybe two light passes with the sandpaper at most) to remove the sharp part that is the result of the manufacturing process. This will extend the life of the reeds by removing the "stress riser" where cracks and fraying can develop. Use blue Loctite on the screws and do not over-tighten them when installing.

While you have the reeds off the cage, you might take a small file or Dremel tool to match the manifold, if necessary, to the cage to give a little better flow. It usually does not take much to reduce internal turbulence and the price is right-free.

The D36 needle usually works well and the middle groove is a good place to start. The #35 can be a little lean for some engines so if you have any off-idle problems, consider a #36 or #38 pilot. Switching to a #80 starter jet really aids cold starts (or use a .031" drill to enlarge the #60 jet). The 120 main can be a little rich so you might end up with a #118 or #116 main jet.

There is no standard final setting for the air/fuel and idle speed screws. You'll want to set the idle speed with a warm engine, in gear and the clutch lever pulled in normally (not all the way to the grip). Adjust the fuel screw by quickly blipping the throttle from idle (warm engine) and adjusting the screw in/out for the best response. The fuel screw final setting will vary with temperature, humidity, barometric pressure etc., and is the reason why it is adjustable.

Jon

[gordeee]

Hi

Thanks for the replies, most helpful.

I'll take your advice on installing the reeds and post my findings.

I guess its trial & error and a coffee cream coloured plug would look okay.

Once again thanks

Gordie

[jse]

Hi

Thanks for the replies, most helpful.

I'll take your advice on installing the reeds and post my findings.

I guess its trial & error and a coffee cream coloured plug would look okay.

Once again thanks

Gordie

Each engine is a little different and it will be time well spent to fine tune your

bike to the conditions you run it under.

The milk-chocolate color plug is not an absolute and Trials engines are somewhat

different when it comes to plug readings. You will probably find your plug will end

up having a slightly darker color in most cases when it is running fine. In Trials engines,

plug color gives a much more general indication of mixture condition due to the lower

RPM range using several overlapping carb "circuits" and the on/off throttle settings,

rather than just the needle/main settings under relatively constant load that most

other competition engines run under. The plug color will be a good "gross" indicator

of carb tuning but the engines behavior is what you will use to tune it. Trials engines

will cough, bog, rattle, stall, sputter, hiccup etc. when they need attention in the carb

department, so keep track of what your engine does and the conditions under which

it does it so you can post the results and other riders can help you get it sorted out.

Good luck.

Jon

[copemech]

Each engine is a little different and it will be time well spent to fine tune your

bike to the conditions you run it under.

The milk-chocolate color plug is not an absolute and Trials engines are somewhat

different when it comes to plug readings. You will probably find your plug will end

up having a slightly darker color in most cases when it is running fine. In Trials engines,

plug color gives a much more general indication of mixture condition due to the lower

RPM range using several overlapping carb "circuits" and the on/off throttle settings,

rather than just the needle/main settings under relatively constant load that most

other competition engines run under. The plug color will be a good "gross" indicator

of carb tuning but the engines behavior is what you will use to tune it. Trials engines

will cough, bog, rattle, stall, sputter, hiccup etc. when they need attention in the carb

department, so keep track of what your engine does and the conditions under which

it does it so you can post the results and other riders can help you get it sorted out.

Good luck.

Jon

Hi Jon, is this another example of (what time is it)( how to build a watch) mode!

Do you need more coffee? ( I here he got a new bike soo he is all pumped.)

Edited September 15, 2010 by copemech

[jse]

Hi Jon, is this another example of (what time is it)( how to build a watch) mode!

Do you need more coffee? ( I here he got a new bike soo he is all pumped.)

Ah Copey, my Texan Luddite friend.

Just trying to add some "why" to the "how" of engine tuning and maybe clear up some possible

misinformation in the process.

No new bikes, but I think I need some more coffee......

See you at the Octobertest?

Jon

[copemech]

Ah Copey, my Texan Luddite friend.

Just trying to add some "why" to the "how" of engine tuning and maybe clear up some possible

misinformation in the process.

No new bikes, but I think I need some more coffee......

See you at the Octobertest?

Jon

If everything Jon says is true, it may work, but you gotta try it !

Jon, I really do need a week off work! I could arrange things for you to come down and help out in my absence. Within that period, you should be totally exposed, ready to kill someone you have never met, ready for a vacation due to tech overload, go back home and become a Luddite!

[gordeee]

Hi Gordie.

Here's a few tips that might help:

Before installing the Boyesen reeds, use a little 600 grit wet/dry sandpaper to very, very lightly radius the edges of the reeds (maybe two light passes with the sandpaper at most) to remove the sharp part that is the result of the manufacturing process. This will extend the life of the reeds by removing the "stress riser" where cracks and fraying can develop. Use blue Loctite on the screws and do not over-tighten them when installing.

While you have the reeds off the cage, you might take a small file or Dremel tool to match the manifold, if necessary, to the cage to give a little better flow. It usually does not take much to reduce internal turbulence and the price is right-free.

The D36 needle usually works well and the middle groove is a good place to start. The #35 can be a little lean for some engines so if you have any off-idle problems, consider a #36 or #38 pilot. Switching to a #80 starter jet really aids cold starts (or use a .031" drill to enlarge the #60 jet). The 120 main can be a little rich so you might end up with a #118 or #116 main jet.

There is no standard final setting for the air/fuel and idle speed screws. You'll want to set the idle speed with a warm engine, in gear and the clutch lever pulled in normally (not all the way to the grip). Adjust the fuel screw by quickly blipping the throttle from idle (warm engine) and adjusting the screw in/out for the best response. The fuel screw final setting will vary with temperature, humidity, barometric pressure etc., and is the reason why it is adjustable.

Jon

Hi Jon,

All sorted, I've spent a fair amount of time but has been worth it. I'm happy with the combination of 38 & 116 main.

I tried the various permutations and the bike pulls nice and smooth with this set up.

The #80 starter made the bike a little more difficult to start, so the #60 has gone back in.

I did profile the edges of the reeds but declined to alter the cage & manifold, maybe another time.

Many thanks again

Gordie