engine upgrade articles and options

[johnny LIS150]

can anyone point me to a good article about engine upgrading options please ?

I'd like to have an overall appraisal about upgrading and stage tuning ,exhaust tuning ,carbs etc for a LIS150 engine . There are so many options available I'm totally confused.

I'm not looking for a fire-breathing monster just an engine that is suitable for cruising / touring and good acceleration . I'm definitely not looking to spend thousands £

[bristolmod]

FWIW I've removed the original top end to my LI150S and have done the following:-

Got hold of a TV175 cylinder; "186" head (64mm); and a quality 64mm piston.

Had the barrel bored to 64mm to match the piston with 3 thou clearance.

Retained the existing 18mm carb with jets!! (taken many plug chops and no problems....), and fitted a 42mm Clubman exhaust.

The bike is a lot quicker through the gears and will sit happily at 55MPH for miles on end.

Have had NO nip ups and , touch wood, is very reliable. Ran in on short hot/ cold cycles.

Whilst its not a rev monster it is a lot better to drive on todays roads and a cheap conversion.

The only downside is that it tops out in each gear fairly quickly- I may simply fit a 16T front sprocket and appropriate chain.

Worth considering.

Chris

[johnny LIS150]

thanks Chris thats really useful personal feedback . Its one thing to read an article on tuning but its rare to read a test review .
Your upgrade sounds like just the thing I need , easy and economical with a modest but worthwhile performance improvement.

I did buy a cheap 200cc cylinder piston and rings kit for a 150-200 upgrade a while back but I've no information about it. It came with a head stamped 175cc ?
I might try that as long as it doesn't involve changing conrod etc .

55mph doesn't sound a lot but I suspect that it will be quite fast enough for windy twisty country roads It might feel a little slow when cruising odd sections of motorway but I can look at the gearing and perhaps sacrifice some acceleration for a slightly better cruising speed

Have you noticed what your RPM is at 55mph ?

[bristolmod]

RPM at 55 sounds quite high- hence the possibility of a 16T front sprocket in due course.

The kit you've bought may be worth a try- where did it come from? Is it one of those iron sleeved alloy jobs? I've tried quite a few of those with generally good cheap results. The beauty of those is that they are relatively cheap compared with the Mugellos etc, and if it does go wrong its not the end of the World.

Generally those kits will need tidying up in the ports areas, and you have to be aware of clearance issues as regards piston vs bore ( I tended to get hold of cheap alloy/ iron cylinders and a 66mm piston seperately and get my friendly one man machine shop to bore accordingly)

As regards tuning , it is feasable, although I tend to restict myself to raising the exhaust port a tad and elongating it slightly- generally its "suck it and see" but the results have been OK and its enjoyable having a fiddle.

One thing, over the years I've gone DOWN on piston vs bore clearance and tend to run 3 thou (in old money) on cast iron set ups and 2.5 thou on iron sleeved alloy barrels. Many people will consider this way too tight but with carefull running in (short sharp cycles) its been OK with me.

Re the head- it should be a 175 thats been taken out to 66mm or so- if its at 62 mm (175) then don't use it).

Be aware that boring a 150 out to 200 cc (58mm to 66mm) is leaving the walls very thin indeed- its better if it was a 175 cylinder (62mm) to start with.

Have a play and see how you get on- you will be learning all the time!

Chris

[johnny LIS150]

this is the kit I bought .
its an aluminium cylinder with a steel liner
http://www.ebay.co.uk/itm/271407847535? ... 1439.l2649

I should have measured the bore and piston before boxing it up and putting it at the back of the shed

I'm not too bothered if it doesn't prove useable as I haven't lost much but the guy assured me that the other kits he sold were all useable .

WHat I'm looking out for is a spare engine and crankcase so I can just swop it over and always have a spare .