Gori 200 jetting problems

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Lamaddict
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Thu May 17, 2018 11:32 pm

Also running a 22 Jetex on a small block conversion with a drilled air box. I ended up with a 130 main. I found a Trail Tech temp gauge a great help for jetting. I put the lead onto the cowling bolt, over 78c it was getting too hot. Now it’s jetted right I can comfortably ride full throttle and keep a eye on the temp. It’s nice to ride full throttle and see the engine cool down.

scandical
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Sat May 19, 2018 7:25 am

Thanks again for the advice. I also had similar thoughts about being lean at WOT and too rich lower down. The temp gauge is a good idea but I'm trying to keep the scooter original looking as much as possible.

lambretta.co.uk suggest that if the scooter splutters off of throttle and clears, that it may also be down to a too rich slide. I have a 5914-1 fitted.

Which number slides are leaner?

I know a PHBL would be the sensible path to follow, but surely an sh should be workable as I have only mildly tuned it (pipe and larger cylinder)!

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HxPaul
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Sat May 19, 2018 8:56 am


Adam_Winstone
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Sun May 20, 2018 7:35 pm

Providing there is nothing wrong with your carb and you use it through the right combination of components then you'd be perfectly able to set it up correctly.... Just watch of for poor advice from and/or feeling the need to listen to people who might want to sell you stuff.

Your motor will set up perfectly with 22 SH carb, PHBL, PHBH, VHSH, or virtually any carb! People might suggest something that they feel is better to suit their riding style or performance target but that is simply their opinion, which is valid but no more 'right than any other.

Last weekend I rode to a dynos centre with 3 pals on road tuned motors and 2 of us were running air box filtered SH carb on iron barrels, one being 200cc and the other 230cc, and both motors run as sweet as a nut.

Get your carb and air intake sorted and an SH carb can perform very well with your kit.

Adam_Winstone
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Sun May 20, 2018 7:40 pm

Further to the above, the Scootering 'Bang for Buck's feature showed that a standard carb can work very well in a mild port iron barrel. Your Gori kit has porting fairly similar to the SIL factory IV and you can benefit from reading the early stages of setting that example up.

scandical
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Sun May 20, 2018 9:55 pm

Cheers Adam, I'll look up the scootering article.

Today a pal dropped off a Jetex 24 to try out. It came with a 48 idle, and 135 main, and I fitted a 5899-2 atomiser.

It was hard to start but ran okay for about 20mins doing about 40mph, when it started performing strangely when I was off the throttle (kind of revving up and down with clutch in/engine jerking when I had it in gear).

I stopped and it didn't start again until I had kicked it a few times - luckily I was by home then. I'm thinking the idle and main are too large and it's getting too much fuel - will try 45 and 130 next.

Jetting in is blooming time consuming!!

Adam_Winstone
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Mon May 21, 2018 1:01 pm

Again... watch out for atomiser. I just had my 200 dyno'ed with 5899-4 (much weaker at low throttle positions) and a 132 MJ, running a Dellorto SH2/22 reamed to 24mm. A/F/ ratio showed this to be correctly jetted through the range.

Watch out for anything Jetex... some are perfectly OK but others suffer from fuel starvation and odd running. The sizes of jets are all over the place and should NEVER be trusted!

Adam

Adam_Winstone
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Mon May 21, 2018 7:22 pm

NB: If you do get around to trying a 5899-4, please note that I've suggested running with a MJ no smaller than a 120 and possibly considerably bigger. Whatever you do, please don't go trying one with a small MJ or you are very likely to damage your motor!

I don't know how well you've set up the other elements (e.g. ignition timing, squish, compression ratio, etc.) but I recently had a look at a pal's iron 175 that was dealer kit supplied and that a geometric compression ration of lower than 7:1, which shows why it is worth checking everything yourself. I would use ALL setup recommendations as a starting point for you to then corroborate through careful testing. Have you marked up your throttle grip and housing to accurately carry out choke tests at each of the throttle positions?

Unfortunately, I can't give you any more specific setup details as each engine will differ based on other aspects of your motor's configuration.

Best of luck.

Adam

scandical
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Tue May 22, 2018 6:00 pm

Thanks for the good advice Adam.

The Gori seems to be working well at idle and when accelerating through the gears (not got anywhere near WOT yet mind).

The Jetex24 now has a 125 MJ, 48 idle and 5899-2 set up. I fitted a self made (3D printed) mesh grit filter too - the BGM filter was still too restrictive and made the engine splutter.

I haven't got round to checking the squish yet and just plugged the Gori on when rebuilding. I also fitted a new GP crank and Casatronic (variable) set at 24*

If it continues to perform as it did after my first run, and assuming the plug chops are good, it would seem we have a winner... :)

Adam_Winstone
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Tue May 22, 2018 6:32 pm

Hmmm, I run a BGM filter on a modified airbox on a 238cc motor with 30mm PHBH and that is not too restrictive, which makes me question whether the BGM is actually the issue or perhaps the airbox that you're trying to run it through, or possibly a combination of factors.

I have run, and have mates running (just dyno'ed), 22mm carbs on 225cc + motors through standard Lambretta filters and they are far more restrictive than the BGM item.

Anyway, it sounds as though you are getting somewhere with it. Just make sure that you keep checking and stay safe.

Adam

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