General Category => Engine & Transmission => Topic started by: Scooter4 on April 22, 2022, 08:49:47 AM
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Good morning,
I have gotten back to my K model project and have attempted to start the engine. It will try to idle but is spitting a lot of fuel out of the carburetor. It will not speed up. When I had the engine apart, I knew the rotary valve and engine case has a lot of damage and I think that is keeping it from running.
I am wondering what others have tried to repair these items? I am looking for ideas before I try either making an oversized rotary valve and machining the case to fit, or sleeving the case to fit a smaller rotary valve. Possibly smearing JB weld on the surfaces to fill in voids and refinishing to original size.
Please let me know of things that have been tried.
Thank you,
Scooter
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Post some pics of the damage , if you have them .
Not sure if Wayne would have a replacement valve or not .
Pete . :)
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I do not have it apart yet, but will take some when I do.
Thank you,
Scooter
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Good evening,
I found that I have an ignition problem I did a different post about. I also found the engine was flooding I did a different post about. I did get it running though and I think it will tune in enough to at least drive if I can get the other problems fixed.
Thank you,
Scooter
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Good it's running .
At least you have a base to work from .
Pete . :)
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Good evening,
I am checking all the parts while I have this engine apart and it looks like someone has increased the length of the rotary valve cutout by a fair bit. This affects the crankcase pressure while the piston is on the way down because it seems to me like it closes too late and will force mixture back out of the carburetor and also make it not pump the charge into the combustion chamber well.
I am wondering if anyone has one of these valve to take measurements from to compare? Refer to attached images.
Thank you,
Scooter
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I took a look at a couple of these. Outside Diameter = 2.056" Then I measured across the opening as pictured. Both compared to one another. I agree with the slot starting by the keyway as you have outlined.
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When I got my '48 the rotary valve had worn down and the block had worn out. The intake hose between the breather and the carb was torn. I speculated that the engine had ingested too much dirt. In an effort to keep the bike original I machined a sleeve to renew the block. It was kind of tricky as that is the same bore the crank bearings fit in to. I duplicated exactly what the bore looked like on the inside of the block. At the time (1992) I had very little contacts for parts so I sleeved the rotary valve back up to size. Clearance is .0025" per side.
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Good morning,
Thank you for taking the time to check parts. I was just about to reply to that when you post of the sleeve arrived and that is great you did that.
Mine fits snug, but has a lot of scoring because someone sandblasted the engine and did not cover that and filled the engine. At some time before I bought it, the flywheel had been rotated at least a few times to damage the surfaces. Unfortunate.
So I measure my slot and it is 1.7" using calipers (my metal calipers are not digital so you cant see it good enough in a picture). The hand grinding starts on mine after 1.47", so it has been modified quite a bit and I bet it was hard to start.
I am going to make a new rotor and that will fix the matter of valving and scoring on the surface.
Thank you,
Scooter
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Good evening,
I have started making a new rotor and I am wondering if you know why the keyway is blind? Maybe for assembly purpose to keep from being installed backwards. I am hoping we have a broach and bushing at work that will fit. Otherwise, I will drill and file or try the shaper.
Please let me know.
Thank you,
Scooter
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It is a blind keyway. Open to the hollow side. Perhaps you are right about simplex doing that for assembly purposes. Looks like .875" bore but keyway measures .136" 9/64"?
Can't wait to see your end product!
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Good evening,
attached are images of my new rotor. I am blessed to work at a place I have access to broach and mill because I only have a lathe and drill press at home.
It took a long time to make because I had to stop a lot to check for exact measurements on OD and width, I do not have an adjustable reamer and the bore is a pinch bigger than .875 for slip fit.
Thank you,
Scooter
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That is Beautiful! Great work.
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Looking sweet!
Scooter, are you coming to Portland for the meet in June?
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Thank you for the complements!
I used to go to some swapmeets, but probably wont again until I retire in a decade. I hardly have time for now.
I will have to log back in later, some electrical storms are approaching.
Thank you,
Scooter
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Scooter, if you’re not retiring for a decade, you must be the youngest guy in this site! Lol :)
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Very nice work on that rotor , Scooter .
Pete . :)
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Good evening,
Also thank you to you to Pete for the compliment on the work.
Not many left younger that interested in motorbike or engine restoration. It is disappointing.
Thank you,
Scooter
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I think there's actually more than a few that are interested . Just that there aren't many that have or can even afford a Simplex to work on . And , how many have ever seen a Simplex or know that they exist .
i'm always educating folks as to what my '57 is .
Pete . :)
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Good evening,
I decided to fill in the scoring in my rotor valve bore by smearing in a thin layer of JB weld and swiping it with a box knife blade so it is only as tall as the high points of the scoring. I think it will help.
I am not worried about the fuel affecting it since it is epoxy. I did soaking samples several years ago leaving the samples submerged in gasoline, alcohol and acetone for a year with no noticeable affect. Also not worried about it coming loose. If it does, I will fix it.
Ignore the debris in the block, I promise I will clean it before I put it back together.
Thank you,
Scooter
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Hello all. I am a newbie to the site but have owned a 48 Exactly like Kartjockey's for almost 50 years. I am planning an engine rebuild/refresh complete with bore and oversize piston/rings, bearings, etc; I have noticed carb blow-back and suspected rotary valve clearance issues were the fault so, this thread is of particular interest to me. Many THANKS for sharing your findings. Its good to know that Im not sailing alone on this one and can consult the guys in the know! Scooter4... thats an outstanding job you did on that rotary valve!! .002 clearance? Oh yeah!
Guess my next step is to remove the engine for tear down and have a long careful look to assess things. What to do about the RV clearance thing has had me scratching my head a while now but, I wont know how bad things are till I have a look. Wish me luck. Thanks again, guys!
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Hello all. I am a newbie to the site but have owned a 48 Exactly like Kartjockey's for almost 50 years. I am planning an engine rebuild/refresh complete with bore and oversize piston/rings, bearings, etc; I have noticed carb blow-back and suspected rotary valve clearance issues were the fault so, this thread is of particular interest to me. Many THANKS for sharing your findings. Its good to know that Im not sailing alone on this one and can consult the guys in the know! Scooter4... thats an outstanding job you did on that rotary valve!! .002 clearance? Oh yeah!
Guess my next step is to remove the engine for tear down and have a long careful look to assess things. What to do about the RV clearance thing has had me scratching my head a while now but, I wont know how bad things are till I have a look. Wish me luck. Thanks again, guys!
Welcome DynoDan . :)
Pics of your bike , please .
Pete . :)
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Good evening and welcome DynoDan.
Maybe after you get a chance to check the crank bearings for play if you need to just fix a little scoring in the block you can try smearing in some slow set JB weld like I did. I have not run it maybe an hour but seams to have stayed in place. It did not take long to do.
The good part of the bearing bores on each side of where the rotor valve runs was close enough together to use a new box knife blade as a straight edge to smear in the JB weld and clean off any that is anywhere but in any scoring with the box knife blade for sure in the snap ring grooves. Dont want to leave any build on the bearing bores or they wont go back in.
Good luck.
Scooter
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Yeah Scooter4, the JB slow epoxy is by far the strongest as is true with most all epoxies. And making sure the surface is spanky clean!
I wont know till I have a look inside what Im up against but am prepping the 'surgery room' (my dining room) to rcv the Servi after I put the flat tracker in the garage. Here are some pics as requested. Not sure exactly how to attach the pics...Hoping this works.
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Well, that didnt work and the 'help' link for uploading pics was of little use. Help! Thnx
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Maybe :
http://simplexservi-cycle.com/index.php?topic=234.0
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Well, that didnt work and the 'help' link for uploading pics was of little use. Help! Thnx
Dan, did you get the private message I sent you a couple of days ago? If not, let me know, and I can send you an email with my phone number.