Figure 53
| NEW PISTON MEASUREMENT CHART
Measurement in Inches |
||
| 250 c.c. 72 mm | ||
| Metric Size | Inch | |
| Standard | 72 mm | 2.8334" to 2.8344" |
| 1 st oversize | 72.20 mm | 2.8414" to 2.8424" |
| 2nd oversize | 72.40 mm | 2.8492" to 2.8502" |
| 3rd oversize | 72.60 mm | 2.8570" to 2.8580" |
| 175 c.c. 61 mm | ||
| Standard | 60.90 mm | 2.3960" to 2.3968" |
| lst oversize | 61.10 mm | 2.4040" to 2.4048" |
| 2nd oversize | 61.30 mm | 2.4118" to 2.4126" |
| 3rd oversize | 61.50 mm | 2.4200" to 2.4208" |
| PISTON CLEARANCE CHART | ||
| MODEL | PISTON TO CYLINDER
CLEARANCE |
NEEDS REBORE IF
CLEARANCE EXCEEDS |
| 250 Pioneer | .00175" - .002" | .0045" - .005" |
| 250 Plonker | .001" - .0015" | .0035" - .004" |
| 250 Stiletto | .002" - .0025" | .0045" - .005" |
| 250 T.T. & D. M. R. | .0025" - .003" | .005" - .0055" |
| 175 Pioneer | .002" - .0025" | .0035" - .004" |
| 175 Stiletto | .0025" - .003" | .0045" - .005" |
4. Clean the cylinder inside after the liner is removed. Check for any damage or score marks from removing the old liner. Sand them lightly with fine sandpaper. Be sure not to remove too much metal.
5. Put the cylinder back in the oven and heat to 400 to 450 degrees.
6. Remove it from the oven and support it right side up by the lower
fins so the new liner can be inserted without touching the bench.
7. Hold the new liner so the ports are close to being aligned with
the ports in the cylinder.