So, it appears I have a D7 barrel, but a D10 piston and head. The rings are scrap (gap well above the 13 thou limit), but the piston (+20 thou) is very good, and the barrel is decent. I would gladly replace just the rings, but they're probably going to be harder to find and most the cost of a complete piston, in which case am I better off the +40 thou piston and honing the barrel out to make it perfect.
The rings as I measure them are 1.62mm thick and 2.50mm wide, although obviously being worn, the width may be misleading.
If I do replace the piston for another D10 job and keep the D10 head, does that mean the carb is going to be too small and need work or replacement? Added to that, how do I tell the difference, and I think I'm missing the plunger on the carb, although not quite sure what the function of this is anyway.
Thanks for reading!!
January 9, 2013
carb dawings always show all parts that can be be fited some carbs are fited with alll the bits like plunger choke its not needed as the air filter has a choke on your carb ,, bantams can be a miss mach in the change of a MODLE so get wot you have going befor binning good parts the D 10 number aplys to the crankshaft as some had 3 or 4 gaers ,the D10 3 g cases are also able to cary a d 7 crank as i found out
Had it running, sounded horrible and wouldn't rev, but that was because of worn big end and piston rings more than anything I assume. The engine itself is an FD7 so I was wondering if it was best trying to go back to standard D7 parts as I'm looking at possibly a new piston anyway, or stick up minimum spending and keep the d10 piston and head.
June 23, 2013
April 19, 2018
June 23, 2013
that looks more like a D14 cyl head it has a slightly wider squish band to the D10
has your conrod small end a bronze bush or a needle roller bearing
will make a difference as to what piston you can fit
has the piston a flat top or slightly domed
the problem will be ignition timing the D14 has a higher compression ratio to the D7 so needs to be retarded more then the D7
and you dont really have enough movement on the stator to do that
D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/
Coco - thanks, I'd seen that, but was planning to modify to size if necessary anyway, just trying to find a starting point to work with.
Mike - the piston had two rings and a slight dome on it, the small end bearing is a roller type. I think I'm leaning towards just changing the rings, as long as I can find the right width and thickness, I can modify the circumstance and add the notch if necessary.
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