Scooterotica

just fitting a mbd rerofiled head to my mates ts1 and noticed the plug comes thru a long way anyone else had this ,,,did you use extra washer ..

are u using a long or short reach plug?

Had this alot with Indian cylinder heads... its nothing to do with the skim and reprofile, just that the plug thread is left a little short when originaly machined......Which allows the plug to protrude a little too far into the combustion chamber.....Try fitting an extra plug washer to sit the plug furthur back in the thread.....It helps a little..... Ideally the plug should finish flush with the cylinder head's internal surface with only the original washer in place, allowing more surface contact between plug and head, which creates better cooling of the plug through the greater contact area of the thread of the plug with the cylinder head.... A few years ago I went to Scooter resterations and sorted a couple of heads out for myself with Pauls permition, as some are deeper than others...This is not a new problem...

yea long never noticed before bur if the head been reprofiled mean a certain amount of alloy has been removed therfore it will come thru more than before

spock64 wrote:yea long never noticed before bur if the head been reprofiled mean a certain amount of alloy has been removed therfore it will come thru more than before

Material is only usally removed from the squish band area and not the combustion chamber...

J1MS wrote:

spock64 wrote:yea long never noticed before bur if the head been reprofiled mean a certain amount of alloy has been removed therfore it will come thru more than before

Material is only usally removed from the squish band area and not the combustion chamber...

unless the chamber has been altered


Leigh

To get the two cylinder heads I was going skim and reprofile to use on two conversions.... I had to sort through a stack of well over 50 Indian cylinder heads before I had obtained the two that I was going to use...The quality seems to change from batch to batch.....But your right in what you say Leigh if the chamber has had material removed to alter the compression after being skimmed this could well cause the problem.....

didnt quote your post to try and say you was wrong J1MS, was just pointing out chamber could have been altered, as pretty sure MB do to lower compression.

Leigh