Search found 532 matches

by Rich_T
Sat Aug 08, 2020 4:40 pm
Forum: Lambretta Tech
Topic: GT186 piston skirt question
Replies: 5
Views: 809

Re: GT186 piston skirt question

Yes, it is fine to trim the bottom of the piston skirt up by 1mm but with a 110 rod it should be a couple of mm clear in any case
by Rich_T
Wed Jul 29, 2020 11:19 pm
Forum: Scooterotica Tuning & Maintenance Information
Topic: Balancing a lambretta crank/top end??
Replies: 5
Views: 3348

Re: Balancing a lambretta crank/top end??

There is no need to match rotational masses of primary drive and flywheels this has nothing to do with crank balance BUT the flywheel should be finely balanced, ideally dynamically balanced. Crank balance on a single is always a trade between forced axially up and down the cylinder (forces along the...
by Rich_T
Wed Jul 29, 2020 10:30 pm
Forum: Lambretta Tech
Topic: GT186 piston skirt question
Replies: 5
Views: 809

Re: GT186 piston skirt question

Where did you get the piston from? The standard piston has is 0.75mm clear of the crank case with a 58 stroke & 107 rod. With a 110 rod the clearance will be an ADDITIONAL 2mm from standard. It sounds like you have the wrong piston to me. If you send me pictures or details I have 64.75 pistons in st...
by Rich_T
Mon Apr 27, 2020 12:55 pm
Forum: Lambretta Tech
Topic: GT186: ideal cylinder cowling?
Replies: 4
Views: 747

Re: GT186: ideal cylinder cowling?

Scooter O Pacific might have some in the US.
by Rich_T
Mon Apr 27, 2020 12:52 pm
Forum: Lambretta Tech
Topic: GT186: ideal cylinder cowling?
Replies: 4
Views: 747

Re: GT186: ideal cylinder cowling?

yes and yes. Series 1 heads are a good fit and also later series (without scoop if you prefer). You have to cut the cowling to fit around the read valve so you can also trim it to have a better fit for spark plug clearance. Gran Turismo manufacture longer cylinder head nuts, you can buy them online ...
by Rich_T
Sat Apr 11, 2020 11:18 am
Forum: Lambretta Tech
Topic: GT 186 with or without standard filter.
Replies: 3
Views: 615

Re: GT 186 with or without standard filter.

remove the filter totally and run through the airbox but make sure it is all cleaned out and free of debris. This assumes that you have a suitable air hose, the airbox internals are removed or the minimum diameter of the inlet pipe into the airbox is larger than 25mm.
by Rich_T
Sun Mar 01, 2020 12:02 am
Forum: Lambretta Tech
Topic: Ignition systems
Replies: 15
Views: 2270

Re: Ignition systems

Another option is RS125 conversions. This is a DC generator system, from Nippon Denso, using donor CDi from Aprilia RS125 including the ECU. I do a conversion system for GP tapers and all the new big engines exclusively use this process. There is a build manual available, it isn't a conversion for e...
by Rich_T
Sat Dec 14, 2019 9:51 pm
Forum: Lambretta Tech
Topic: Granturismo 200cc piston oversize stockists
Replies: 13
Views: 1858

Re: Granturismo 200cc piston oversize stockists

also checked the DT175K compared to the RD350YPVS (piston used on original GT200's) on the TKRJ manual. This states a 0.5mm lower crown height on the DT175K piston. This would increase the port timings a little, if you send me port heights I can calculate what the effect would be or you could use se...
by Rich_T
Sat Dec 14, 2019 8:43 pm
Forum: Lambretta Tech
Topic: Granturismo 200cc piston oversize stockists
Replies: 13
Views: 1858

Re: Granturismo 200cc piston oversize stockists

I checked this information again. According to Mitaka/Grampian data the DT175K piston has the same compression heights as the 350LC piston. The dome height is 1.5mm higher but that isn't the end of the world. Over-sizes for this piston will take you to 67.5mm as I understand.
by Rich_T
Mon Nov 18, 2019 7:34 pm
Forum: Lambretta Tech
Topic: GT186 manifold - carb fouling engine mount
Replies: 10
Views: 1537

Re: GT186 manifold - carb fouling engine mount

The GT manifolds are symmetrical but that doesn't mean they fit properly when rotated around. The general advice is fit them the way there are designed for. The TM24 is popular in USA but other than some reports on the jetting I don't know how they went about clearance issues, the first manifolds di...
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