Jump to content


Photo
- - - - -

Tiger Cub PVL Timing


  • Please log in to reply
4 replies to this topic

#1 brucey

brucey

    Advanced Member

  • Members
  • PipPipPip
  • 126 posts
  • Location:Hythe, Kent
  • Bike:Triumph Tiger Cub
  • Club:Sidcup MCC

Posted 04 March 2011 - 06:20 PM

Hi,

I am just building the engine for my Trials Cub Project. I am fitting a PVL ignition which I purchased second hand about a year ago. I'm sure Alan Whitton said set the timing 5mm BTDC but the guy who sold me the ignition said 2.0 - 2.5mm BTDC.

I'm running a +40" 7:1 piston and 'R' Cam in a Square barrel, side points engine.

I know Alan uses a higher compression Kawasaki piston (I've got one but couldn't bear to bore a perfictly good barrel).

I can just about get both timings but would like to set the correct timing in the middle of my adjustment.

I'll be running the engine on a Mikuni VM22 (26mm) pit bike carb if it makes any difference to the timing as I believe these are the kiddies to fit.

Also, what valve clearances do you use for an 'R' cam?

I was also going to do the mod that puts a plate in the head to make fitting the push rods easier. Does anyone have any photo's or sketches of this?

It's taken me a year on and off to build this bike but I can see the light at the end of the tunnel now!

Any help would be appreciated.

Bruce.


Ads By Google User is online

Ads By Google
  • Ad Bots


Don't want these Ads? Why not help support TC and sign up as a Trials Central Supporter?

#2 old trials fanatic

old trials fanatic

    Advanced Member

  • Members
  • PipPipPip
  • 2,715 posts
  • Location:Derbyshire
  • Bike:James Bulto TY Ossa
  • Club:Peak Classic, Dales Classic, AA, Tufty.

Posted 04 March 2011 - 07:55 PM

Hi,

I am just building the engine for my Trials Cub Project. I am fitting a PVL ignition which I purchased second hand about a year ago. I'm sure Alan Whitton said set the timing 5mm BTDC but the guy who sold me the ignition said 2.0 - 2.5mm BTDC.

I'm running a +40" 7:1 piston and 'R' Cam in a Square barrel, side points engine.

I know Alan uses a higher compression Kawasaki piston (I've got one but couldn't bear to bore a perfictly good barrel).

I can just about get both timings but would like to set the correct timing in the middle of my adjustment.

I'll be running the engine on a Mikuni VM22 (26mm) pit bike carb if it makes any difference to the timing as I believe these are the kiddies to fit.

Also, what valve clearances do you use for an 'R' cam?

I was also going to do the mod that puts a plate in the head to make fitting the push rods easier. Does anyone have any photo's or sketches of this?

It's taken me a year on and off to build this bike but I can see the light at the end of the tunnel now!

Any help would be appreciated.

Bruce.

All i can say is i've known Alan a long time and IMHO he knows more about PVL ignition than anybody else i've come across so i would go by what he told you. He can also help with the mod for the pushrod fitting.

I thought a VM22 carb was 22mm which would be normal for a Cub whereas a 26mm would be a VM26 which is a bit larger than most of the people i ride with use.

Jack the Lad will probably be along soon with his advice as i know he does work on Cubs for Bob Moore and he also advocates the use of pit bike carbs so can probably advise re those.

Ignition timing shouldnt be affected by the carb size or jetting i have found.

Good luck with the build BTW

Edited by Old trials fanatic, 04 March 2011 - 07:59 PM.

The Victor Meldrew of Trials Central. Dont believe everything you read about me because the truth is much much worse !! LOL

#3 brucey

brucey

    Advanced Member

  • Members
  • PipPipPip
  • 126 posts
  • Location:Hythe, Kent
  • Bike:Triumph Tiger Cub
  • Club:Sidcup MCC

Posted 04 March 2011 - 11:51 PM

OTF,

Thanks for the information.

I just wasn't sure how much difference the piston and cam make to ignition timing. I guess I can always phone Alan and ask! (he has never been anything but helpful).

I have seen the fantastic job Alan does on the push rod inspection hatch but will have to do it myself as I spent the remainder of my budget on one of Alans cnc machined gear change levers instead!

I have also recently discovered Classic Dirt Bike Mag and obtained back issue 16 which has an article on the Comerford Cubs. In the Article Donald from Armac reccomends setting the clutch using a DTI. I'm assuming you operate/disengauge the clutch and adjust the 3 springs until the pressure plate runs true (using the DTI to check). Has anyone else done this?

The VM22 Mikuni carb advert said the following in reference to its size:
"PLEASE NOTE 26mm IS THE WIDTH OF THE OUTLET SIDE. THE SLIDE IS 22mm."



Bruce.

#4 superhondaman

superhondaman

    Advanced Member

  • Members
  • PipPipPip
  • 257 posts
  • Location:Leicestershire UK
  • Bike:Fantic 200, Cub
  • Club:ESTC/Leamington Victory

Posted 05 March 2011 - 09:10 AM

OTF,

Thanks for the information.

I just wasn't sure how much difference the piston and cam make to ignition timing. I guess I can always phone Alan and ask! (he has never been anything but helpful).

I have seen the fantastic job Alan does on the push rod inspection hatch but will have to do it myself as I spent the remainder of my budget on one of Alans cnc machined gear change levers instead!

I have also recently discovered Classic Dirt Bike Mag and obtained back issue 16 which has an article on the Comerford Cubs. In the Article Donald from Armac reccomends setting the clutch using a DTI. I'm assuming you operate/disengauge the clutch and adjust the 3 springs until the pressure plate runs true (using the DTI to check). Has anyone else done this?

The VM22 Mikuni carb advert said the following in reference to its size:
"PLEASE NOTE 26mm IS THE WIDTH OF THE OUTLET SIDE. THE SLIDE IS 22mm."



Bruce.


Get in touch with motocarb and get the VM20 the smaller carb is better suited to the 199 cub.

#5 jack_the_lad

jack_the_lad

    Advanced Member

  • Members
  • PipPipPip
  • 109 posts
  • Location:Lancishire
  • Bike:Triumph Tiger Cub
  • Club:Rochdale

Posted 05 March 2011 - 09:23 AM

Hi,
First thing you need to ask is how good a rider are you? If you set your PVL to five mm BTDC you might find it responds a little too quick. I personaly would not use an R cam. Will let you know about the Mikuni carb just about to try one this afternoon. I would also use the Kawasaki piston.These are not very high compression.
Jack

I am just building the engine for my Trials Cub Project. I am fitting a PVL ignition which I purchased second hand about a year ago. I'm sure Alan Whitton said set the timing 5mm BTDC but the guy who sold me the ignition said 2.0 - 2.5mm BTDC.

I'm running a +40" 7:1 piston and 'R' Cam in a Square barrel, side points engine.

I know Alan uses a higher compression Kawasaki piston (I've got one but couldn't bear to bore a perfictly good barrel).

I can just about get both timings but would like to set the correct timing in the middle of my adjustment.

I'll be running the engine on a Mikuni VM22 (26mm) pit bike carb if it makes any difference to the timing as I believe these are the kiddies to fit.

Also, what valve clearances do you use for an 'R' cam?

I was also going to do the mod that puts a plate in the head to make fitting the push rods easier. Does anyone have any photo's or sketches of this?

It's taken me a year on and off to build this bike but I can see the light at the end of the tunnel now!

Any help would be appreciated.

Bruce.






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users