Avanti

[Captain Pugwash]

Is anyone from this forum running an Avanti 225 kit with a 60mm stroke crankshaft ?

was hoping for some feedback ?

Cheers Mark.

[MickYork]

I'm interested as well......

[mark1]

I'm interested as well......

Me too.

[Scooterlam]

What is it you would hope to gain.

[Adam_Winstone]

Capt.

I'm hoping that this means that you're now looking to put your Avanti on the road and considering your options. Knowing the attention to detail that you put into your engines, I'll be watching this with interest.

60mm into an Avanti... no, not yet. However, I've currently got one that I've just put a 60mm stroke HPC crank (107 rod... rather than the more common 110 that is 'trending') into and is on the bench. The Avanti that I'm building is not standard anyway so I don't think that my info would have much bearing on your question anyway.

What I can say is that you need to ad'dress the skirt length as the standard TT3 piston is pretty long and the extra travel at BDC can be a factor on some cases.

Watching with interest.

Adam

[Psychedelicropcircle]

I have a bgm one in mine. Smooths it out a bit. The lack of zuarsts that fit is my only problem (clubmans)

[Captain Pugwash]

I decided on a Harry Barlow built 60mm x 110mm crankshaft. Im hoping it will be here some time this week

[rossclark]

Be interesting to see if that extra 3mm causes issues with fitment of the cowlings, exhaust or frame given the extra size in the barrel and head.

[Adam_Winstone]

^... good point as the standard Avanti TT3 assembly uses up pretty much all of the available area anyway.

[Captain Pugwash]

Be interesting to see if that extra 3mm causes issues with fitment of the cowlings, exhaust or frame given the extra size in the barrel and head.

I think your right, its going to be a very very tight fit, I'm almost certain there will be a little adjustment needed when its done but I think it will be worth the extra effort

[Captain Pugwash]

This is the 60x110 "Harry Barlow" built crankshaft I'm fitting to the Avanti, the barrel will need a mild tweek to the ports to suit the longer stroke.







The barrel assembly will move by 4mm, and as some have mentioned it might make the barrel a tighter fit when in the scooter.

[coaster]

Mine has a 3mm packer and there are no clearance issues with the top end at all, series 80, Indian 200 case, 300mm rear shock and standard cones in the frame.

[Captain Pugwash]

Packer fitted for 60 stroke 110 crank.



Port timings rechecked on new rod and stroke.



As it is now with staggered "transfer port timings"





Both main transfers inked for marking up maximum port modification.



One main transfer showing a negative port roof entry angle the other is the same.


Better view of both transfers marked up prior to any cutting.

[Blaginit]

Hi all,I'm fitting 60mm crank and have been told to fit 1.5mm base packer and remove 2mm of piston.being a bit of a gork what advantages would this 60mm crank give.My reason for fitting is I've got brand new crank and it seems a waste not to use it,how much would it affect jetting, cc size or do you think I'm out of my depth and I should stick to standard .

[rossclark]

60mm stroke will give you approx 5 extra cc taking it to 230 on a 70mm bore.

Is yours a standard 107mm length rod? If it is then I'd start with a 1mm packer and check the timings and the squish and work from there.

Taking 2mm off the bottom of the piston might be for two reasons -

1. To prevent the skirt banging on the casing with the longer stroke, the piston goes 1 mm further up and 1 further down, sometimes they can catch at BDC
2. To increase the inlet timing. This can lead to increased spit back on a piston ported motor if you go too far.

I'd think carefully before doing that and check what the clearances and timings are like. Measure carefully and recheck it several times before you cut anything.

No harm in using the crank but you'll have to jet it to what suits it rather than something arbitrary.

[Blaginit]

Cheers thanks for that

[Adam_Winstone]

FYI - My Avanti TT3 top end didn't miss a beat during my 900 miles in 4 days of getting to Mannheim (Germany) before I decided to call it a day and return home (450 there and 450 back). We spent a number of hours at 70+ on motorways, holding that speed as a constant cruising speed with plenty left for overtaking.

I ended up wimping out after shearing a layshaft and hub, which I replaced for the return leg, but it was nice to have absolute confidence in the top end. I only had the plug out once to check colour and it was a glorious chocolate brown

Great kit!

Adam

[MickYork]

Just got a 60mm crank so would appreciate any info' on the builds that are going on.

Ta

[mark1]

FYI - My Avanti TT3 top end didn't miss a beat during my 900 miles in 4 days of getting to Mannheim (Germany) before I decided to call it a day and return home (450 there and 450 back). We spent a number of hours at 70+ on motorways, holding that speed as a constant cruising speed with plenty left for overtaking.

I ended up wimping out after shearing a layshaft and hub, which I replaced for the return leg, but it was nice to have absolute confidence in the top end. I only had the plug out once to check colour and it was a glorious chocolate brown

Great kit!

Adam

I agree with everything you've said about the kit Adam. Unfortunately I hole'd the piston in mine on the way to ebensee. I didn't even make it out of the country.
I tried everything possible to get it set up right for the trip, dyno, loads of high speed motorway miles, cht gauge, check, check check. Unfortunately it hole'd at 65mph doing 5,900 revs (I've done over a dozen runs of 10 miles at 7,000 revs, 77mph with no problems what so ever)
Ah well, new piston and barrel re-line then I can start again.

[Adam_Winstone]

What a shame!

I've noted your other thread comments about having had the bike dynoed and I'll keep an eye out to see how you get on with it.

Adam