1923 Chief rebore ?

[Ken Lee]

Hello , does anyone know the maximum rebore that is safe on a blind bore 1923 Chief 74 inch please ??
Mine has nasty gudgeon pin lines that a previous rider ignored and kept running .
Many thanks and have a great Christmas and lotsa nice Rides in 2019 . Ken

[hairynob24]

G,day Ken these old barrels are very thin around base nut recess area . if I had my time over again I would have had them cylinder inserts around the 40 th size .and have a pistons made smaller to gain more life out of them , there is a company in the USA called Dinihanian Manufacturing who can build up the bore with Nikasil to 40 th ,this maybe something to look into ,they have an add in the amca mag page 15 … I think 60th is about the limit you can go . JD jugs here in Oz did talk about remaking them at one stage but nothing has come of it yet ,Rob

[Ken Lee]

Thanks Rob , yes would be nice to be able to get new cylinders , mine are standard bore and have been rebored 20 thou which still leaves gouge marks . I'll ask the firm doing the rebore if they can build up the bore with Nikasil , good idea . They say they do not think 40 thou will get rid of the marks and I don't really want to go much further , as you say , they are very thin cylinders ! Thanks , Ken

[Tom Wilcock]

I have taken early engines apart that had the pin grooves in the cylinders brazed up sometime in their past. They were obviously run many miles after with no apparent problems and the bores were still serviceable.
Tom

[Ken Lee]

Thanks Tom , I did ask about brazing them but they didn't want to in case of distortion !! but I will ask again and also about the Nikasil . Best wishes , Ken

[gharper]

Ken,

I ran my 24 chief with +.040" oversize pistons and .0065-.007" clearance on the last cannonball, dragging a sidecar. Never had any problems. I would be comfortable running them at =.050" oversize, but not more than that. The other thing I did was to cryogenically treat the cylinders and valve springs to relieve stress. It's a common process used on high stress engine parts.

The Nikasil process is a great way to go, if you can find a place that will do it on a blind cylinder. Shaky Jake here on the forum may have a source for that...... He mentioned it regarding Powerplus cylinders a while back on his powerplus or bust thread.

Sleeves are OK, but not ideal. If done, I like the idea of finishing the bore smaller, as opposed to boring way out and inserting a sleeve.

Gene

[Shaky Jake]

Ken,

I ran my 24 chief with +.040" oversize pistons and .0065-.007" clearance on the last cannonball, dragging a sidecar. Never had any problems. I would be comfortable running them at =.050" oversize, but not more than that. The other thing I did was to cryogenically treat the cylinders and valve springs to relieve stress. It's a common process used on high stress engine parts.

The Nikasil process is a great way to go, if you can find a place that will do it on a blind cylinder. Shaky Jake here on the forum may have a source for that...... He mentioned it regarding Powerplus cylinders a while back on his powerplus or bust thread.

Sleeves are OK, but not ideal. If done, I like the idea of finishing the bore smaller, as opposed to boring way out and inserting a sleeve.

Gene

I was surprised how well your Scout pulled that sidecar, Gene, especially in the end when you decided to turn it lose a little bit!

I ran sleeves in my Powerplus in this years Cannonball and they worked fine, but I hate the idea of removing any more metal than you have to from old original parts. I have a set of cylinders in my shop now that I had nikasil'd by U. S. Chrome in Fondulac, Wisconsin (I think they have their own name for the process, I can't remember at the moment). I haven't run them yet, but the bores are very pretty and are back to original size. The folks at U. S. Chrome were good to work with, you just get on their website and fill out a work order, and then ship the cylinders to them. They didn't have any problems with the blind bores.

Kevin


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[Ken Lee]

Hello Gene , well done on the Cannonball and thanks for your comments . I have asked for .0045 clearance , would you advise .0065+ , using modern aluminium pistons ? I agree with the smaller bore if relining , I'll have a look for Shaky Jake's thread . Many thanks , Ken

[gharper]

Kevin and Ken,

Thanks for the kodos on the cannonball. Even though we had a magneto problem that made us loose a few miles one day, I'm still proud of the old girl for making the miles every day! The Indian Chief did well too!

Ken, I went with the looser clearance because I was forced to. My initial set up on the top end failed on the front cylinder within 50 miles, it scored the hell out of the bore! So, honed out until it cleaned up which was another +.012" or so. That put me at the .006-7" number. I honed the other cylinder to match as it was already +.040 over anyway. With a bit looser clearances, break in is much easier, plus my engine ran HOT, pulling a sidecar and 2 people plus all our gear, tools, extra gas etc. To split hairs, I'd go .005" minimum with cam ground aluminum pistons, but I would prefer .006". I just don't like fitting them close, piston or ring failure is catastrophic and destroys rare cylinder material. I think I could hear a bit of piston slap from time to time I think, but it was not excessive at all.

Kevin,

I planned all along to run about 45, that seemed to be the sweet spot. As you know, once you get out on the open road all alone and lots of others pass you up, there is a strong temptation to speed up a bit. I fought it for a while but gave in, and it was actually a good thing! If I hit hills of any size at 45 or less, it would bog down and with careful adjustment of the throttle and spark it would settle into a grind and pound its way up the hills, sometimes having to grab 2nd gear for a bit. I found that if I hit the hills at 48-49 mph, it would often hold that speed with less throttle, or even accelerate! To cruise on the flats at anything above 50 was very uncomfortable, it just seemed to fight itself and vibrated quite a bit. It was like a tug boat, it liked to pull hard, but not cruise fast so much!

I'm interested to hear how the nicka sil coating works for you. I've heard nothing but good things about it. It appears to be a good solution for damaged cylinders and is a better material, allowing use of modern oil rings with high tension and reduces friction quite a bit.

Gene

[Ken Lee]

Hello Gene , so glad the old girl did well (and the Chief) , I have a Princess sidecar to fit , had it on my 101 but is really too heavy for the poor old Scout hauling my old girl and camping gear !!
When I took my cylinders in I said give them .006 clearance but they persuaded me that .004 would be better as the modern pistons 'do not expand as much as the older ali ones' so we agered on .0045 but think after your experience I'll tell them to give .006 . and may have to go .040thou over pistons with '006 thou clearance and hope that will give a clean bore and as you say easier and quicker to break in , I'll also ask them about Nikasil to fill any marks . Hope you don't mind me asking all this but what gearing do you run ?
Many thanks , Ken

[gharper]

Ken,

Here are the MPH vs RPM cheat sheets I had clipped to my handlebars. I flipped from one to the other from time to time to try and get an idea of what a sprocket change would do for me. I never changed gear ratios, stayed with the 22 front and 40 rear sprocket. This gave a 4.63 /1 gear ratio. It worked well overall but seemed almost too low for flat out cruising but maybe a touch too high for mountain use. Maybe a 4 speed would do the trick.......

For the first 25 years I ran this rig I used the 4.85 / 1 and it worked well, but had no top end. Part of that was also the weak original valve springs which worked like a rev limiter. The motor pulled really good until the rpm got up a bit and then it flattened out, absolutely no faster. Looking at the 4.85 / 1 chart I would guess that happened about 3000 rpm or so.

I figured that between the bike, 2 passengers, sidecar, gear, fuel etc we were pushing 1150 lbs. So, the old girl did damn good!Cannonball finish September 23, 2018.jpg


MPH 22 T 4.63/1 7.27/1
3rd Gear RPM 2nd Gear RPM
20 1785
25 1421 2232
30 1706 2678
35 1990 3125
40 2274 3571
45 2558 4017
50 2843
55 3127
60 3411
65 3695



MPH 21 T 4.85/1 7.62/1
3rd Gear RPM 2nd Gear RPM

20 1870
25 1490 2337
30 1789 2804
35 2087 3272
40 2385 3739
45 2683 4206
50 2981
55 3279
60 3577
65 3875


MPH 23 T 4.45/1 6.96/1
3rd Gear RPM 2nd Gear RPM
20 1710
25 1360 2137
30 1632 2564
35 1904 2991
40 2176 3419
45 2448 3846
50 2720
55 2999
60 3264
65 3536

[Ken Lee]

Thanks for that history , very interesting , I have a 40 rear and 21 front which I'll try first otherwise means buying another which will do if I think I need to , you've certainly had time to sort your outfit out , although I've had many outfits , the longest I had was a Harley (sorry) 45 with a Milford sidecar which we went everywhere on (best bike Harley ever made) OK , not fast but always got us where we wanted . Thanks for the pic , lovely lady and bike !! Enjoy , Here's my two Princess's on my 101 bike . Ken
Merry Christmas and Happy New Year to ALL !!
Gearing may be slightly different as am fitting 19 inch drop center rims , not that I don't like beaded edge tyres , I run them on other bikes but the rims that came with the bike are not usable so replacement with modern rims and tyres is half the price and tyres better too .

[gharper]

Ken,

Nice looking princesses!!!! Curious, how did the sidecar fit up to a 101 chassis??? And, how did you get the negative reversed on a digital camera? Oh wait, you drive on the wrong side of the road, hence the left hand sidecar!

I ran 19" Coker Diamond treads on the Cannonball. Before that I always ran 28 x 3 clinchers. the clinchers are about 1" larger diameter. Unless you ride in hilly country, the 22 and 40 will be great for you. The 21 and 40 is very powerful, just a bit low for top end. As I recall, 21 and 40 was listed as standard solo gearing in the early 20's chief opeartors books.

gene

[Ken Lee]

Hello Gene ,
Thanks BUT tis you who ride on the wrong side of the road and fit the bike to the ''pretty side'' of the bike !! Anyway , I had to make and adapt some fittings I had and it worked out ok , still using the original ball and socket fittings though . Handles great just a bit slow but I don't mind , I have plenty of time to get places over here as nowhere is that far till you hit water !! That pic was taken in Holland at The Oldtimers Rally and yes , most of us are getting older but it does refer to the bikes - pre 1966 American bike rally . I have a long way to go , see pic , everything I got was in bits , including all the races and bushes out of the engine cases !! bits missing , not all the same year etc but it'll be a good rider (hopefully) when done ! Have a nice day , Ken

[gharper]

Ken,

Looks like a 22-23 fender and a 24-26 fork, spring and link assembly. Seems the 23 chiefs are popping up all over.