Scooterotica

Darrell Taylor wrote:id be interested in you checking the squish again using 2 blobs of plasticine along the gudgeon pin line coated in oil as think it will be nearer 1mm/1.1mm

then measure down from top of cylinder to top edge of transfer and ex port with a digital vernier depth gauge,look very carefully and u get a really accurate measure

ex 33 / 33.2 transfers 45.9 is what i normally see ,there very consistent very old kits and the latest batch are well cast but the odd rogue one exists

i reckon how u have it is ok and as you say its easy to juggle around ,poss lose 1 base and add a std head gasket of same size will be better still

Much appreciated Darrel, I'll get fiddling and measuring tommoz, I've all week working from home and the Mrs is in Saudi

reason i mention the squish is the 4 solder will normally over compress the crown and measure the deflection of the small and big end and mains so can give a slight false reading

Darrell Taylor wrote:reason i mention the squish is the 4 solder will normally over compress the crown and measure the deflection of the small and big end and mains so can give a slight false reading

But wouldn't that compression be the same as when the engine is running? There would be load on the big and small ends due to the forces impossed by the compression and detonation process surely?

Thinking about my port timings, could the irregularity be caused by the deck hight? Only the case is a small block (indian GP150) converted to large block.

cheers

colin

if you have a squish of 1.3mm with 4 pieces of solder then have a squish of 1.1mm with plasticine its a useful measure to know you can use it to check wear ,the differance of 0.2 will initially be under compression on the up stroke but at higher rpm youll get rod/crank/bearing stretch of approx 0.6mm on a 58mm stroke plus piston accelleration out runs the clearance being closed up by compression then the thin crank web width will allow a little more travel along with increased wear over the life of the motor can leave the piston touching if a little too tight
i dont think the port timings are irregular they are what most people measure but hoping for a eureka moment to come soon when u do the remeasure in mm measure to roof of port duct not the mild chamfer

Darrell Taylor wrote: i dont think the port timings are irregular they are what most people measure but hoping for a eureka moment to come soon when u do the remeasure in mm measure to roof of port duct not the mild chamfer

Measurements come out as 44.9mm on the transfers and 32.20 exhaust, how to they sound?

My temporary workshop is now glistening with sparly aluminium grindings as the result of half an hours angle grinding to open the fins up. I think I'll leave the far side as that side is not covered by the cowl.

did you have the vernier zeroed or have you deducted 1mm for squish?
i measured 5 kits yesterday old and new and all were very accurate 33.2 45.9 +- 0.1mm your 32.2 44.9 is exactly 1mm out on both measures so possibly a mismeasure?
just took a new one from box and 33.27 45.86 thats an average on the transfers each were +- .05

coaster wrote: My temporary workshop is now glistening with sparly aluminium grindings as the result of half an hours angle grinding to open the fins up. I think I'll leave the far side as that side is not covered by the cowl.

:biggrin: would that be the kitchen? seeing as its cold outside and the mrs is away

Darrell Taylor wrote:

coaster wrote: My temporary workshop is now glistening with sparly aluminium grindings as the result of half an hours angle grinding to open the fins up. I think I'll leave the far side as that side is not covered by the cowl.

:biggrin: would that be the kitchen? seeing as its cold outside and the mrs is away

Not the kitchen but yes, it is inside the house in a room that is 'under development' so to speak

Re the vernier, yes I did zero it and also made sure that the slide was against the cylinder wall, the end is notched so I had the longer bit closest to the cylinder if you know what I mean. I also used a feeler gauge to check when the ports were just opening. I'll have another go.

cheers

colin

i see a potential problem how ur measuring ,i measure the cylinder off the motor as you need to look from the bottom of the bore to see the tip of the vernier in line with the port roof,youll be impressed how accurately you can measure ,
on transfers, find height of 1 then lock off the thumb screw and check the others
when done deduct the squish say 1mm and use edens port calculator (with squish deducted put 0 in the deck height as it can be confusing with the + - )

Right, barrel's off again, I messed about with the vernier and eventually got figures in the range that Darreel quoted above. Very difficult to be completely consistent though as from the top ot bottom of the barrel you are not looking squarely at the roof of the port. Anyway, I just fed the figutres into Eden's calculator and it gave 176.5 exhaust and 124.7 transfers. Then I spotted the bit about deducting the squish so with 1mm removed from both measurements it comes out at 129 and 180 (I had already entered the piston to crown hight as zero.....what do you think?

Spent the rest of the day fettling the new gear selector to get it to work, had to grind loads off to stop it fouling on the case