alloy 197 kit spitback/flooding

[Adam_Winstone]

Well done for circumnavigating the issue by swapping out the top ends. As you say, there's something wrong with that top end, whatever it may be. They tend to be very soft and wear out as quickly as they are run in so not really viable as a long term option.

Whilst the inlet duration quoted shouldn't have been an issue, I wonder whether if the position / relationship of the ports is causing issue, allowing too much communication overlap? Also, some postons have a steeper angled side than others (imagine the side angle of a thimble), with the original SR pistons being rumoured to have been questionable. If the side angle is steep then the cutting short could leave excessive clearance to the piston, causing rocking and slap... although rings should be stopping excessive blow-by, if suitably gapped.

^... probably enough of your time wasted on that cylinder though!

Thanks for letting us know.

[shamrockexpress]

Adam it was an Asso piston new giving a clearence of 3 to 4 thou, ring gap 0.3 so no slap........i mentioned earlier i was suspect to the position of the inlet port so much that the std gp150 22mm manifold was so close to the engine mount the sh22 carb wouldnt fit!!!!!!!
i will now measure all the ports in relation to two sr185 cylinders i have an let you know the results. (case opened again)

[Adam_Winstone]

Do note that my wonder is not port durations but, rather, where they are in relation to one another, i.e. overlaps of the 360 degree rotation, rather than standalone durations. You may get an indication of something being out by comparing physical port dims in relation to barrel length (typically from head gasket face).

There's certainly something up with it

[coaster]

Whilst the inlet duration quoted shouldn't have been an issue, I wonder whether if the position / relationship of the ports is causing issue,

Could there be something up with the port angles, thise indian SR type barrels are pretty grim as supplied with the heights all over the place and questionable angles. There is a resent SLUC video where Rayspeed demonstrate how the ports are supposed to flow by squirting water up the transfersand inlet ports, they are supposed to meet in the middle of the combustion chamber.

[shamrockexpress]

Whilst the inlet duration quoted shouldn't have been an issue, I wonder whether if the position / relationship of the ports is causing issue,

Could there be something up with the port angles, thise indian SR type barrels are pretty grim as supplied with the heights all over the place and questionable angles. There is a resent SLUC video where Rayspeed demonstrate how the ports are supposed to flow by squirting water up the transfersand inlet ports, they are supposed to meet in the middle of the combustion chamber.

Valid point Coaster, yes i seen Ben squiting the ports. Very simple and interesting, will give that a go just to see. Will be needing the slow motion video on as it squirts really fast.
Hopefully all this video squirting is being taken in the proper context .

[Adam_Winstone]

[shamrockexpress]

On cylinder inspection compared to two other indian 185s the transfers where 1.5mm lower, transfer direction looked like the other cylinders so ok ish and the seal between liner and alloy jacket looked a bit suspect,,,,,,,,,,although didnt leak in leakdown test, plus compression was really good.......
all in all i,m convinced cylinder was at fault!!!!
Several more projects to get on with so we have now
scooter running and will be up for sale soon.
1963 series 3 LI125 (175) , italian import 2004 so rust free all solid.
any intrest PM here

CASE CLOSED

[Warkton Tornado No.1]

Update,

Taking into account the piston skirt had been cut by 5mm this is likely to blame

I’m sure I speak for many in that - as a Club devoted to Lambretta - we try to help fellow members where we can.

Only now do we learn that there is 5 mm off the inlet skirt, which would surely have increased the inlet duration substantially, yet the figure for our consideration was quoted at 145°, not wild by any means.

It’s difficult to give an accurate assessment in any endeavour to be constructive in helping &, in this instance, somehow, the actual information conveyed was almost certainly not factual……

[shamrockexpress]

Sorry warkton , 3mm not 5mm