VTR1000.ORG

incredible!!!!!

Lovely neat work there Vara

Chris.

Cheers guys

I'm looking forward to the delivery of a Mazda Rx7 jetted 45dcoe weber. Should get it tomorrow

Lots more gussets to fit & working out if I need some midships if there's room. I feel like I'm on a roll with the frame now all the major decisions (tank/seat/exhaust position) have been made.

Getting there slowly, but I do feel that real progress is being made now

There are no two ways about it, you are moving forward without a doubt

Fingers crossed your twin choke Webber turns up tomorrow,

Chris.

The last time I saw a Webber was on my Cortina Pinto

sirch345 wrote: ↑Fri Jun 01, 2018 8:46 pm Fingers crossed your twin choke Webber turns up tomorrow,

It did Chris

Right then, the carb (Weber 45 dcoe) arrived yesterday.

It’s complete, it's filthy & looks well used. All the threads are ok, so it should work when it’s jetted properly.

I stripped it down & the jets are as follows.

Choke --- opened up on a lathe to 40mm.

Auxiliary Venturi --- 4.5 but slightly squeezed (ovaled) due to over tightening…

Emulsion Tube F11.

Idle jet 85 - F9.

Main Jets 165.

Air Corrector 160.

I was after a 48/50/55 dcoe tbh. Then this was spotted, it was cheap & because it was previously jetted for a high reving ****el engine I might be able to salvage some jets in the process.

Right then Carl, thank god someone has some solid dcoe tuning skills behind them, because I haven't

I've read lot's of info on dcoe tuning & have come to the conclusion that you can tune these carbs to run perfectly on any engine configuration, but patience is required. The majority of the information though is about engines that rev to 6000rpm..

Here's a diagram of what's recommended/required for engines that rev higher.



Looks as if I've got problems already

I can't see any image in your last post.

Sorry mate your on your own with this one. That's out there in the wild sticking them on a VTR. Get them running though and it will be awsome. It's been years since Iv'e touched anything like that and TBH I have forgotton most so wouldn't know where to start. Well actually, the first thing is to strip and clean them and work out what is what. I can see there being a lot of trial and error here.

VTRDark wrote: ↑Sun Jun 03, 2018 3:34 pm I can't see any image in your last post.

I have the same issue with IE9'ish & duckduckgo.

It works with firefox though

I'm only joking about being a dcoe tuning god Carl

But I agree it's going to be a challenge that's for sure. Any & I really do mean any ideas from anyone about dialing in these carbs will be greatly appreciated

I'm running with the idea that 40mm chokes will have to do atm, & are the biggest chokes for these carbs & they're still too small

The chart indicates that the 45 is way too small but it's all I've got.. If it runs out of steam @ 6000rpm so be it

My plan of attack is to use the 40mm chokes & follow the ball park guidelines.
------------------------------------------------------------------------------------------------------
Main Jet and Air Corrector Size Selection.

A useful formula for the calculation of main jet size when the main venturi size is known is to multiply the main venturi size by 4.

This will give a starting point for the main jet size which should be 'safe', again as a starting point the emulsion tubes can be selected from the table shown below, although for Pinto F9 or F16 will generally be OK.

If your carbs are already equipped with these, then that will save you some money.

Air corrector jet initial settings should be around 50 higher than the main jet.

Main jet size Venturi size * 4

Air corrector Main jet size + 50

Emulsion tube Selection.
Below is a table showing suggested emulsion tube type, for a given single cylinder capacity.
Cylinder capacity Suggested tube.

250-325cc F11
275-400cc F15
350-475cc F9, F16
450-575cc F2

The 2000cc Pinto in just on the cusp of change for emulsion tube type between F16 and F2, if you
already have F16 tubes, use them it is not worth the expense of change, they will just cause the
main circuit to start marginally earlier. A 2.1 or 2.2 Pinto should however be using F2s although
F16s will do the job acceptably well.

Using these formulae, a venturi size of 40mm will require a main jet of 160 and an air corrector of
around 210. Fitted with a emulsion tube type F2.

What do you all recon ?

Forgot to mention,

Below is a chart showing approximate idle jet sizes for given engine sizes, this assumes one carb barrel per inlet port E.G. two DCOEs.

Engine size Idle jet size.

1600cc 40/45
1800cc 45/50
2000cc 50/55
2100cc 55/60

Establishing the correct idle jet for a given engine is not easy but usually an approximation will make the car acceptably driveable.
If the progression is weak then the engine will nosedive when moving the accelerator from smaller to larger throttle openings.
A certain amount of change (richer/weaker) to progression can be achieved by varying the air jet size on the idle jet; this alters the amount of air that is emulsified with the fuel drawn through the idle jet.
If this does not richen the progression sufficiently then the next jet size up, with the same air bleed should be tried.
Below is a small chart showing the most commonly used air size designations, running from weak to rich.
Generally speaking start your selection with an F9 air bleed.

Weaker Normal Rich
F3 , F1 , F7 , F5 ,F2-F4 ,F13 ,F8-F11-F14,F9 , F12 , F6
The ones in normal use are F2,F8,F9 and F6.

Again, using these formulae, a venturi size of 40mm will require a main jet of 160 and an air corrector of
around 210. Fitted with a emulsion tube type F2 & an Idle jet of 50/55.

Sounds easy

My head hurts reading all that lot...yours must be banging

VTRDark wrote: ↑Sun Jun 03, 2018 6:19 pm My head hurts reading all that lot...yours must be banging

Banging, your right there, I'm just back from a trip to Wigan for a Vtr engine I don't really need

I'm glad your twin choke Webber carb turned up, this looks complicated

Chris.

Odd how thinks turn out.

One minute I'm looking at how to tune a Weber 45 for the bike & 15 minutes later I'm on my way to Wigan to collect an engine I don't really need

I saw it on eBay.. it was cheap so I bought it for the manual cam chain tensioners



I gave it a quick once over & all seems ok.

Then I was on a roll so I focused on the Weber.

Varastorm wrote: ↑Tue Jun 05, 2018 10:31 pm Odd how thinks turn out.

One minute I'm looking at how to tune a Weber 45 for the bike & 15 minutes later I'm on my way to Wigan to collect an engine I don't really need

I saw it on eBay.. it was cheap so I bought it for the manual cam chain tensioners

I like it

The carb is looking a lot better for a strip down and clean

Chris.