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Pictures Posting Not Working (12 Jun 2023)

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Makotosun

1971 RT1-B engine seizure UK

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1971 RT1-B engine seizure UK was created by skasa

Hi all. Looking for some advice please….

Seller mentioned the bike had a new top end, probably rode less than 100miles and the motor locked up. I have stripped it mostly (about to split the case) and am wanting to order spares. 

A few questions. 
  • piston is currently 1.0 - I’m wanting to go back to std and put a new barrel 
  • struggling to find a Conrod kit. Does it share the DT360’s? 
  • any idea what could have caused the seizure? My guess may be an air lock on the pump
  • it has a vape ignition and was using an iridium plug on full synth 2stroke oil
thanks for any helps or tips 

Kyle 
28 Jul 2025 06:49 #1

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  • MarkT
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Replied by MarkT on topic 1971 RT1-B engine seizure UK

Best practice would have been to pressure/vacuum test the engine before disassembly to check for air leaks.  

Unlikely to be an oil pump "air lock" or anything to do with the oil pump.  Just doesn't happen much.  More likely ignition timing, improper jetting, or an air leak (lean air/fuel mixture) caused the issue.  

Important to determine the cause or risk a repeat failure.  Pictures of the failed parts can usually give an expert a pretty good idea of what happened.  

Rod kits are available.  Since you are in the UK, I''d try PJME for the engine work like the rod and reconditioning whatever cylinder you use. My guess is they could inspect the carnage and get a pretty darn good idea of what caused the failure.  
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
The following user(s) Liked this Post: swm, Ht1kid
28 Jul 2025 08:27 #2

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Replied by 1971DT250 on topic 1971 RT1-B engine seizure UK

I have a NOS cylinder with standard, first oversize, second oversize pistons and rings. Send me a PM if you're interested.
I'm in the US.
The hours spent riding my Enduros is not deducted from my life span.
28 Jul 2025 12:40 #3

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Replied by skasa on topic 1971 RT1-B engine seizure UK

I can’t seem to upload any images, not sure why. 

ive reached out to them and they don’t have any rod kits available

thanks for the info. 
28 Jul 2025 13:43 #4

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  • pahiker
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Replied by pahiker on topic 1971 RT1-B engine seizure UK

You need a certain number of posts before you can load pics. This is to defeat scammers/spammers. You need to use a 3rd party app like imgur or Google photos to post pics, direct upload doesn't work.
1973 Yamaha RT3
2024 Suzuki DR650
2023 Triumph Tiger 1200 GT Pro
28 Jul 2025 16:03 #5

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Replied by Rick C. on topic 1971 RT1-B engine seizure UK

There is one on Ebay U.S .
Bikebuzzard2
$150.00
Yamaha MX360 DT360 MX DT 360 130mm Rod Kit w/25mm Crank Pin NEW!

Type or copy and paste that in, for some reason it won't let me copy the link and paste it in.
28 Jul 2025 16:18 #6

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Replied by Gr8uncleal on topic 1971 RT1-B engine seizure UK

Yamaha MX360 DT360 MX DT 360 130mm Rod Kit w/25mm Crank Pin NEW! | eBay
28 Jul 2025 23:10 #7

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