Kitting Tomos A3

So I'm ordering the Airsal 10mm cylinder kit for my Tomos A3 Golden Bullet. Also getting an estoril sidebleed pipe and mlm 20mm intake with vm20 carb along with an assortment of jets from 135-170. I'm keeping the stock gearing 26/22. This should allow for wheelies in first gear and decent acceleration from 0 into the mid 40's. Running 10w30 synthetic oil in gearbox. Anyone disagree with this overall setup?

Re: Kitting Tomos A3

Can't say I've ever seen a 10mm cylinder kit . ;)

Re: Kitting Tomos A3

10mm refers to the wrist pin size on the A3. The kit displacement is actually 44mm

Re: Kitting Tomos A3

Ahh , Thanks for that^ . ;)

Re: Kitting Tomos A3

I agree with everything except the oil in your transmission. I have been out of the tomos game for a bit, but I believe you want to only run an ATF in your tranny. They make some good racing ones for drag cars running automatic. I got one that is blue in color and definitely more viscous than the regular red ATF.

You also might not get the wheelies you want unless you change out he second gear spring to have it shift later. It will shift pretty early with a nice kit on there as it is all based on rpms. I know with my za50 I wasnt able to do wheelies until I flipped the second gear and caused the shift to happen later.

Re: Kitting Tomos A3

♣Slew Foot♣ /

Marvel mystery oil 4. Synthetic atf.

Blaster oil.

It will let it slip to higher rpms before it warms and becomes tacky.

Re: Kitting Tomos A3

Marvel Mystery oil by itself? Or along with synthetic atf?

Re: Kitting Tomos A3

Also does the Marvel Mystery oil still allow for more slip for both a cold and warmed up engine?

Re: Kitting Tomos A3

Overpriced Parts /

> Jay Rivett Wrote:

> -------------------------------------------------------

> I agree with everything except the oil in your transmission. I have

> been out of the tomos game for a bit, but I believe you want to only run

> an ATF in your tranny.

No most A3 engine clutches are different then a A35 as the clutch lining material is asbestos not junky cork so you can use synthetic motor oil for good results,

But the problem with a3’s is they are geared extremely low, lower then a a35 and have brass con rod small end bushings not needle bearings like a a35/a55 so pushing high rpm with power ruins the crank bushing so you’re getting 2 bad things on a A3 over a a35 so kitting any Tomos engine you can still have issues,

You’re better off in the long run just stock modifying it by just putting an upgrade carburetor, exhaust and gear on, maybe a little porting and calling it a day,

I did/do that with every Tomos I had, ran them for many miles then sold them still running with nothing busted,

Re: Kitting Tomos A3

My conclusion: I'm going to continue running 10w30 synthetic oil in the gearbox. Also keeping the stock top & bottom end (not going to kit to be safe). Ordering an estoril sidebleed pipe and upjetting from the stock 51 to a 56. A better intake and carb (say 15mm or so) along with an assortment of jets and a 27 tooth front sprocket and maybe a 20 rear (stock on my bike is 26/22) is also in this bike's near future.

Re: Kitting Tomos A3

The 15mm mlm SHA a3 intake along with a nice 15.15 dellorto sha carb along with the estoril would be a sensible stock upgrade and with gearing up should get me into the low to maybe mid 40s mph. The sha carb I'm looking at is oil-injection compatible (with nozzle for the oil line on the carb body) but I'm still running 40:1 premix regardless of whether or not I keep the oil injection system

Re: Kitting Tomos A3

If you can get your hands on a stock a35 cylinder and reeds you can run that and cut a window in the stock a3 piston. It should be safe to run with that. The a35 has better stock porting and reeds have better power and throttle response down low. You should see improvement across all rpms if you were to do this.

> Thomas Peffer Wrote:

> -------------------------------------------------------

> The 15mm mlm SHA a3 intake along with a nice 15.15 dellorto sha carb

> along with the estoril would be a sensible stock upgrade and with

> gearing up should get me into the low to maybe mid 40s mph. The sha carb

> I'm looking at is oil-injection compatible (with nozzle for the oil line

> on the carb body) but I'm still running 40:1 premix regardless of

> whether or not I keep the oil injection system

Re: Kitting Tomos A3

Quick question: Will the needle bearing for Tomos a35 fit into the A3 con rod small end (where the wrist pin goes) once I press out the brass bushing?

Re: Kitting Tomos A3

No, but there’s a chainsaw needle bearing that treats carries that will work with an a3 10 pin or the puch bushing in the a3 con rod will fit a 12 pin.

Any of these: https://www.treatland.tv/SearchResults.asp?Search=10x14x13

> Thomas Peffer Wrote:

> -------------------------------------------------------

> Quick question: Will the needle bearing for Tomos a35 fit into the A3

> con rod small end (where the wrist pin goes) once I press out the brass

> bushing? (edited)

Re: Kitting Tomos A3

Thanks Matt!!! You are the man! I'll get to ordering me one (Polini needle bearing 10X14X13). Thank you for your help. Much appreciated!

Re: Kitting Tomos A3

Not a problem, I’m not really the one to thank though lol. Just a little trick I learned, been lurking the forums for 7 years or so trying to learn all the tips and tricks.

> Thomas Peffer Wrote:

> -------------------------------------------------------

> Thanks Matt!!! You are the man! I'll get to ordering me one (Polini

> needle bearing 10X14X13). Thank you for your help. Much appreciated!

Re: Kitting Tomos A3

Kevin Bishop /

Press out the bushing in the A3 Conrod and use the Honda hobbit needle bearing. Ream the inside with 320 sandpaper there is a burr usually in Oiler hole.

Use the compressor oil from harbor freight it’s no foaming. No problem kitting with the 44mm cylinder.

Re: Kitting Tomos A3

> Kevin Bishop Wrote:

> -------------------------------------------------------

> Press out the bushing in the A3 Conrod and use the Honda hobbit needle

> bearing. Ream the inside with 320 sandpaper there is a burr usually in

> Oiler hole.

>

^^No how did the f dis i miss this? Fantastic! the hobbit needle bearing is the ticket.

Re: Kitting Tomos A3

Brandon Weiss (Detective brandon to you) /

The steel that the small end of a connecting rod that has a bushing pressed in isn't designed to handle a needle bearing, it's not hardened/heat treated. The small end will get worn out by the hardened rollers in the needle bearing. Will it work for a while? Probably. Will it fail catastrophically at some point? Probably.

Re: Kitting Tomos A3

Dirty30 Dillon /

Yeah, while it "fits" it is not reamed and hardened to be used with a needle bearing. Not really sure why folks keep suggesting this as a viable, durable solution.

I would rather have the factory set-up brass bushing over a grenade-y needle bearing that the crank was not designed to use.

Re: Kitting Tomos A3

They are in fact hard as dicks, I bored one out to use the standard 15mm/ 12pin bearing and it was definitely in the ballpark to run a bearing, HSS tool wouldn't cut it.

That engine never accumulated much hours but it didn't blow up, and I was sending it pretty hard, calculated 12k based on gps speed and gearing

I still think pressing in a a35 rod is way easier than all these shenanigans, and you know it will last.

Re: Kitting Tomos A3

Dirty30 Dillon /

> Graham Motzing Wrote:

> -------------------------------------------------------

> They are in fact hard as dicks, I bored one out to use the standard

> 15mm/ 12pin bearing and it was definitely in the ballpark to run a

> bearing, HSS tool wouldn't cut it.

>

> That engine never accumulated much hours but it didn't blow up, and I

> was sending it pretty hard, calculated 12k based on gps speed and

> gearing

>

> I still think pressing in a a35 rod is way easier than all these

> shenanigans, and you know it will last.

^^ hardness confirmed, now just to ensure that you leftover hole has the correct tolerances.

Re: Kitting Tomos A3

So the con rod steel is hard enough to handle a needle bearing then?

Re: Kitting Tomos A3

So the needle bearing arrived today and I installed it on the small end of the con rod after pressing out the old bushing using a c-clamp and a 15mm and 8mm sockets. The needle bearings fit perfectly. Sanded down/smoothed out the burrs around the two oiling holes. It went on perfectly without issues

Re: Kitting Tomos A3

Did you happen try the wrist pin in the bearing after you put the bearing in the rod ?

Did it have any play and twist without any hesitation ?

Re: Kitting Tomos A3

Yes I did install the wrist pin and checked for play. Not too tight, not loose. The wrist pin twists (spins) on the needle bearing cage correctly. For anyone who wants to do this on an a3 the dimensions of the needle bearings are 10X14X13

Re: Kitting Tomos A3

Good , so far .

Re: Kitting Tomos A3

So I installed the 44mm Airsal kit made for the A3 this morning along with the vm20 carb/mlm 21mm intake and estoril sidebleed pipe (unrestricted). New needle bearings installed on the con rod small end. Jetted 145 main, 17.5 idle, and needle clip on middle notch. Kept stock 26/22 gearing (for now). Holy fuck this bike does accidental wheelies at half throttle in first gear now and riiiiips all the way past 40mph. Going to take it easy for the first 250 miles or so but for anyone wanting to do this on an A3 you will shit. Bring some toilet paper and an extra pair of pants

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