Ron Moss - Avanti TT3 - Cylinder Kit - Review & Test.....

[Darrell Taylor]

It states power spread is narrow, I would have thought that would be a major disadvantage in a kit being sold as a touring kit? Looking at the dyno charts on rons website it would appear to have a very narrow powerband compared to say an RB225?

ThTs the trouble with dynos they can be very deceptive.
If the chart was to show power to road speed rather than revs (with gearing that the engines can realistically pull) the spread of The Avanti would be wider and something like rb would be steeper.
It's all about gearing, as the Avanti makes it's power lower it will pull higher gearing getting more speed from less revs.
You realy should try riding one.

i find the trouble with dynos is how the graphs are interpreted by the reader ,a power curve with a sharp rise to a high but narrow peak will often be described as peaky
and a wide power curve over a long operating rpm like seen on a clubman will be seen as been really useable
its when you look at the torque curve you can see a clearer picture of what it will ride like on the road and if you then relook at the power curve you can see that the shape that is perceived as being poor is actually favourable ,to maintain torque hp has to keep rising sharply, a levelling off of hp results in a falling torque

[Darrell Taylor]

the negative point about the avanti kit being harder to kick over due to the low exhaust port doesnt really make sense either ..cos its not at all and why would it be because its about compression ratios .

I think it is more a reflection on 'corrected' compression ratios being higher with low exhaust timings, when compared to the same geometric ratio head fitted to a kit with longer exhaust duration and lower corrected ratio. I've also found that mild road tune iron barrelled motors require a fairly hefty kick when compared to some of the revvier (extended exhaust duration) reed kits. In theory the corrected ratio and kick required could be the same between a mildly tuned Avanti 225 and a mega ported high comp (geometric) race tuned RB or other, which seems odd at first glance but makes sense when you think about it.

This goes one stage further when you consider that some of the auto advance/retard kits want to kick back at you at low revs because the motor is firing that much earlier, whereas firing closer to TDC encourages the motor to spin past TDC with comparative ease.

Adam

thats almost exactly what my reply was gonna be until i clicked submit and this popped up
piston port are generally harder to kick (effort on kickstart),but are generally lower on ex duration too

[Diablo]

Having ridden the bike in question and also helped Ron with some of the early dyno testing I would say both bikes are very impressive.
Stickys wifes bike actually pulls up the hill by my workshop in 4th pulling a TV box with the AF road pipe. I can't think of many other bikes that have done that as well.

What I think is a little poor is pulling someone up for giving a balanced view as he sees it. Stickys first responsibility is to his readers. At least he took the time to fit the kit to a bike that could manage the power and then actually tested in real world conditions. I think 150 miles in January to gain performance,reliability and fuel consumption figures is pretty good.

Every Scootering article prepared by Sticky has a list of pros and cons. He does that to give an unbiased view and to furnish the readership with as much info as possible. If you then s**t yourself because you can't put the information into perspective then don't tune a Lammy.
I don't think theres a kit out there that doesn't have a list of cons to go with the pros.

All sand cast kits have issues with ports. Imolas and Mugellos are never out of the box fits but thats engine building. The difference with Rons kit is that he inspects every one and address's any issues before they go out.

One thing I can say is that the coming season will see lots of rally miles on the bike I'm sure with a strip down every now and again to check any wear. This again I'm sure will be reported in an unbiased way.
What good does it do anybody to rave about a kit only a handful have done over a 1000 miles on?

My personal view is that Rons attention to detail and commitment to producing a quality item will show the kit to be a winner and it will stand the test of time. You can't argue with the performance figures or the quality of what you get in the box.
I actually think he's being overcautious about the bridge but that is understandable.
I'm really looking forward to building motors with his kits

[nelson pk]

When i read the review in scootering i knew there would be a lot of comments.
I think the kit looks very good for what it is.
Lets look at some of the cons.......160 degrees is a long inlet timing and we all know you will get a fair bit of spitback with that duration.
Fair comment about about the bridged exhaust.....they can cause issues
It will not perform as good as a reed valve at very low revs simply because its piston port and not as efficient as a reed valve. This is generally well known in the world of two strokes, in fact it is pretty much agreed that piston port is the worst form of induction compared to crankcase and reed but the Lambretta is piston port as standard so it is not to say that the Avanti is not a vast improvement over the standard.
Not wanting to ruffle any feathers but everyone moans about the low transfer duration on a muggy 225 and guess what the Avanti is practically the same and has a long inlet again like the muggy 225.........
Things i like about the kit.......genuine attempt to solve cooling issues on the lambretta. Alloy barrel with nicasil lining. The amount of technical support supplied.
One small concern.......glass fibre head cowling.....i thought it was metal in the pics but i really dont think glass fibre is going to last very long with the vibration of a lamby and constant heating and cooling of the cowling.
All in all great value for money and looks a good kit for what it has been designed to do.
Good luck to all involved.

[Andy Pickering]

The majority of people who will buy this kit will not be bothered about port timings, durations or any other technical jargon that might come to light during the trails of mine and others including Stickys but will simply want to know is it going to be reliable will it not heat seize and leave me stranded at the side of the road when i should be with me mates sinking beer, can it do 65mph all the way to a rally and that's it basically, my experiences will ne based on riding the kit and is it good for town and rally rides not will it do 90mph can i power wheelie in 3rd gear, if i want to do that will get another motorbike , Stickys will be more indepth because he has the knowledge and experiences to do so.

Sent from my GT-I9000 using Tapatalk

[nelson pk]

Please dont misunderstand me.
I say again.....for what the kit has been designed to do its great value and looks good!
I was just pointing out that the article was comparing it to a reed valve motor at low revs and that is not entirely fair as piston port is always going to struggle against reeds there in my opinion.
Also just pointing out that people have slagged off other kits in the past because of port timings and the Avanti has very similar port timings. Not trying to slate either kits.
Agreed, people who want to travel at 60 to 65 all the way to a rally and reduce their chance of seizure, piston failure etc....this kit sounds very good for that!
So, for what its designed for, it looks very good value for money and i do like the larger fin area.
Just to add,for some reason, in the scooter world, people think reed motors are all screaming banshees! (probably because of the kits we've been given with reeds, TS1, RB, Monza). Its the reed induction that improves low to mid rpm power. It has hardly any effect on high revs so maybe a reed conversion on this kit will yield even more low down power?

[Andy Pickering]

maybe a reed conversion on this kit will yield even more low down power?

Stayed tuned in you never what might appear on one of theses test kits over the testing period Oh and Nelson PK you are of course entitled to your opinion

[nelson pk]

So a reed conversion might be on the cards. Will look forward to it
Hope the testing is very successful!

[sideout]

Please dont misunderstand me.
..... people think reed motors are all screaming banshees! (probably because of the kits we've been given with reeds, TS1, RB, Monza). Its the reed induction that improves low to mid rpm power. It has hardly any effect on high revs so maybe a reed conversion on this kit will yield even more low down power?

I'm glad you posted that because I was wondering why all kits weren't reed valve? Oh, and although I've not had first hand experience I thought the torquey GT185 kit had a reed option (but I have been known to be wrong.... usually)
Sounds like a reed version of the Avanti TT3 could improve on what, on paper*, seems to be a great low revving mile muncher.

*Until Andy, Mike, Sticky et al, get some serious real-world miles on them!

Great thread chaps, keep up the good work!

Nigel

[corrado]

The difference with Rons kit is that he inspects every one and address's any issues before they go out.

I can't think of another kit where the ring gap has been measured and written down with the comprehensive instructions sheets. Top marks in my book.
A mate bought a kit and Ron took the trouble to phone him and ask him to check that the head seated in the barrel as he'd sent a couple out without checking them. It was fine btw.