Suzuki RM400 teardown and inspection
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- In this video I do a teardown and inspection of a newly acquired 1980 Suzuki RM 400 engine. I find the engine is still standard bore, the clutch basket shows almost no wear, as well as the rest of the engine and transmission. I perform a spark test and do a measurement of the bore. Which shows that it has very little wear also when compared to 80mm original bore.
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Bought a new 76 RM370 not long after joining the Navy! About 19 years old back then. The bike had about one hour on it and not a scratch! The guy I bought the bike from had recently blown off both his thumbs and most of his fingers on his right hand playing around with M80's. They had removed his left toe and grafted it on to his left hand for a thumb so he would have at least one hand that partially worked and it actually did. Because of the circumstances I didn't try to haggle with him on the price and he cut me a great deal! To this day it was one of the best performing and handling bikes ever! My most recent acquisition is a 2024 KTM300SX. Still fortunate enough to be riding at 68. Always enjoy your videos!
Awesome story Peter, wow some folks just shouldn't get out of bed, I guess. Playing with M80's? Yeah, I was working at a Suzuki dealer when the RM370 came out it was superb in every way to the TM400. I bought my RM400 in 79, and to me it was just about perfect in every way. Great bike, I'm trying to build one from parts. Let's see if I can pull it off. You are right my friend; I have a couple years on you and still enjoy riding. My brain says twist it, my body says, just a little bit though. LOL
Join the crew, im 81 and still ride Dale has a lot of old guys that can still get it up (the bike ) i mean. i have had 17 bikes started riding in 1957 ,today i have a Russian Ural, a 1973 Suzuki TC-100 and a 1974 Honda XL-250.
@@montana2strokeracer Yep! I used to work with an older guy when I was in my mid 40's. He stopped me one day and said "getting old ain't for the chickenshit!" I thought I knew what he was talking about back then. I do now! Lol!
@@frankdillon6127 That's fantastic! I can only hope! I don't want to ever give it up!
Nice / lucky find Dale. Your knowledge of these Suzuki motors always blows me away. Looking forward to seeing it come back together.
Hey Mike, you're sure right about that, lucky find for sure.
GM Dale
Another great teaching video
Keep up the good work and videos I learn a lot from you.
Thank you Mark.
Congrats on your engine! I’m excited to see another series of new videos!
Thanks Troy, me too, probably be a while, still need a lot of parts.
Another excellent video Dale. So glad the engine is turning out to be a winner.
Looking forward to seeing progress on this.
Cheers, Peter.
Thank you Peter!
I'm having a similar hard time finding parts for my '79 KDX 400. but, after 6 years I'm finally almost there!
I know, the Kawasaki's that I have worked on are real difficult to fine parts for. I think that is why folks really like those bikes; they have their heart and soul in them when they are done.
@@montana2strokeracer yeah, i dont think it'll be one i'd sell after it's done. i just want to ride it and enjoy
That looks like you got a heck of a deal on the engine, great score Dale!!
I think so too Don. I had some good luck that day.
Congrats on the condition of it that’s awesome.
Real happy Cain, it sure could have gone the other way.
Can’t wait till the next vid very interesting a big thumbs up from me central United Kingdom 👍👍👍👍👍👍👍
Thanks Steve, I am looking forward to it also.
Nice Purchase Dale, happy for you. Thanks for another great video!
Thanks Jeff.
Another great find there Dale! Have fun with the build of both RM's. They are great bikes and fun to ride! I'm still busy with reconditioning and repairing parts for my projects.
Thanks David, man you work at these bikes harder than me. Keeps us out of the bars. He if you don't mind next time your picking parts, ask around and see if they have a 79 or 80 RM400 frame. Thanks Dave.
@montana2strokeracer I will be heading up to the salvage yard in Phoenix Tuesday and I will look around at their frame stash. Would a RM370 frame work for you?
@davidleland8729 thanks Dave, it really needs to be a 79 or 80 rm400, they made it handle better.
@@montana2strokeracer I came across a 1979 RM400 rolling frame on Reno craigslist for $1500.00. You might want to take a look at it. Doesn't look like it's in too bad of shape
@@montana2strokeracerI came across a 1979 RM400 rolling frame on Reno craigslist. Listed for $1500.00. Looks to be in fair condition. You may want to check it out.
Great stuff Dale, I'm glad you got a good one. Dean.
Thanks Dean, surprise is the word of the day for this one.
I have 2 sets of the Suzuki slide hammer tool and all the accessories that came with it. Never had a problem with them. Suzuki also had a buzz box for timing, and a pressure tester with all the plugs for intake and exhaust. Use to do a lot of 2 stokes in my younger days.
Ah the cool old tools, awesome. Still lovin my two strokes.
Hey Dale I'm from the south of England 👍👍👍👍👍👍👍👍👍
Absolute bargain of an engine Dale most Motorcross engines of the year are pretty beat up.
Your right there Vincent. I was expecting the worst.
Thanks Dale , Dont forget the 380 . Shes calling for you .
Thanks Murray, I won't forget, it's going to be so much work, just the engine as far a cleaning and polishing cases, then rebuilding the crank, I can't even think about it right now.
Had a well used 79 400 in the 80s and was lucky enough to accuire another good example in 2011 and it is my ace today it’ has a .020” wiseco at least it will not crack just takes awhile to warm up before it quits rattling .
Awesome, it was a big mistake for me to sell my 79, I just hope I can find a good frame and other needed parts to put this one back in my barn. These Suzuki's have much more durable cylinders than say.... Yamaha's. When boring them they are much harder material. My 79 was never bored in the 30 some years I had it. I did re-ring it a couple times.
It was a great find!
Thank Bob, I was sure lucky with this one, could have gone the other way for sure.
What a score Dale well done, you sure know your shit ! Very nice work 😊.
Thank you, Darren, I am well pleased, it sure could have gone the other way.
bet the Shushi break bell went off at the Suzuki factory just as the guy was bending the lock washer on the clutch basket, it happens! LOL
Roger that Frank
Good morning Dale, I'm looking forward
Thanks for being here Larry
Another fascinating video, Dale. Interesting to see how the race RM bikes are different from the TS models. lLooks like you've got a sold motor to work with. Look forward to seeing how you repair magnesium cases again.
Thanks Jim, they really are built much like the later TS models. I lucked out on this engine, easy one to build. Yes, welding magnesium is different but thank to you for the training cover to practice on. Sure, appreciate you sending it to me.
Amazing find there, Dale. Everything looks crisp and unworn. Don't know what you have until you tear into it, I guess. Much, much better than the other 400 you're working on. That one must have been apart frequently.
I think so to Doug, very lucky to have come across this engine, now to find a frame.
The trailwizard from the blue sky.✌🏍🏁
Thanks Richard, looking forward to this project.
Great jo b Dale, thankyou Sir
Thanks Blair, this is going to be fun trying to find everything I need for this one. At least the engine doesn't need much.
@@montana2strokeracer Yeah Dale great old air-cooled 2 stroke,,,,,look forward to watching your progress
Nice find, and great video Dale. It's in super nice
shape for sure. Can't wait 'till you get back on the other RM.
Listen, I know a guy that makes custom rings for two strokes. They work better than OEM and I've used a good number of them. He usually makes them for smaller engines, but can probably do a 400 ring for you. At least I think he's still in business. E-mail me if you want his contact info.
Nice work and take care,
Robert
You are right Robert this one is a nice find. I was very lucky, it sure could have gone the other way. I think it will go back as standard; I picked up a new standard piston and ring a couple days ago.
The best thing to happen to that RM400 engine was to end up in your shop. It sounds like you paid top dollar, but you got your money's worth on that one. Looking forward to seeing the progress on restoring it.
Thanks man, I sure was happy the way it turned out, sure could have gone the other way.
Thanks for that
You lost your o ring from the end of the gear set. Your impact screwdriver brings me back to my youth I still got mine 55 years later. I watch your videos marathon style one is not enough. Cheers from Alberta Canada
Thanks Carl, yeah, I found it on the floor. Will need replaced anyway. Thats about how long I have had my impact. One of the first tools my dad gave me. Thanks for the bulk watching I sure appreciate it.
Wow looks can be deceiving that this is like new inside Dale good for you man you won't find another like that again
I know Joseph, I was worried about it, the guy I got it from didn't know anything about it. He got it from a friend.
Hello Dale, great video! Heard you mention Kroil and I wanted to mention the best penetrant I have ever used is MMO cut with 50 to 75% coleman fuel or Naphtha. Looking forward to your next video 🤗 Most cut the MMO with acetone and that doesn't work so well.
Thanks for the tip, Mark, I do use marvel mystery oil and Naphtha is my thinner of choice. Thats what I use on stuck pistons. Yeah, Acetone evaporates too fast for soaking. I will try adding the white gas. Thanks again.
Dale, those 79 & 80 rm400's where sensational nothing in there day sounded like them, usable power was excellent
I totally agree with your assement. The best bike I ever owned.
Repro case covers, billet, rods are available.
Yes, I did know about the rods, but not the case covers, do you have a source you could share, I did some looking last night and couldn't come up with anything other than the sprocket covers from England I think.
Hey thanks so much for this. Also where do I find the crankcase puller as I have a load of TM engines I’m working on and not easy. Separating the cases
Hey Mike, I just used an automotive harmonic balancer puller then found the metric 6mm screws to fit the case. Make sure the puller you get has a bearing type center puller bolt.
Nice find.
Thanks Wayne, it sure could have gone the other way.
Hello Dale, I sent you a post re the ts400 you were working on at the time. Think we mentioned Paul Miller] I did look at the possibility of increasing the cc of the motor by using a rm 465 crank [i think the bore is the same] and using a spacer under the barrel of the ts. I measured the dimensions of the 465 crank assy and thought it might be possible making the ts 400 into a 465. What do you think of that idea? thanks
I never thought to do it. Sounds like a fun project. I enjoy playing with stuff like that.
Since the left case pull did not damage the crank end, would the same puller not damage the crank end for pulling the magnet?
That would be true if the puller bolt fit the puller, but this one didnt. That's why I used the slide hammer.
Hey Dale ! I don't want to be a bore but that looks a good score ! (No pun intended 😅)
That's been a expensive toy for someone with such seemingly low hours.
Regards, Ard
Thanks Ard, you won't get an argument from me. Lucky score for sure.
Hi Dale, great find on that engine! Doesn't look to have had too many hours on it. I am curious about how you store your parts while/after disassembly of an engine. Do you bag and tag each assembly and place them in a box? You seem to have a great memory about how these engines come apart and go back together! Do you use parts diagrams when doing reassembly to find which washer or o-ring goes where? Thanks!
Hey Pete, yes, I was lucky on this one. For parts storage I have red roll around carts. I can get an entire engine on one shelf. Right now, the parts are just placed on the shelf. After the parts are cleaned and inspected, they are bagged to keep them clean. Engines that I am familiar with, I just reassemble, ones I don't see often I sure do go by parts breakdown and the shop manual.
Lol Dale, you need to contain that excitement 🤣
I was trying, guess it didn't work LOL
if crank bearing look good do you replace them while you are inside?
Yes sir
I like your engine vise so useful I didn’t know this can you tell me the brand of this ?
Yes, it is an OTC 7020, try to find a used one. New is insane price. I got mine 15 years ago off Ebay.
@@montana2strokeracerthanks really appreciate
Where can I find an engine stand like that?
Try to find a used one on EBay or something they are proud of them. I bought mine used over 15 years ago. It is an OTC 7020.
Were did you get that engine mount devise?
Hey Mike, it is an OTC 7020, try to find a used one, they are sure proud of them. I got mine off Ebay over 15 years ago.
Hi,Dale!
Thanks for the video, I enjoyed watching your careful methodical work. I just looked on Ebay and there’s a barrel and head on offer at £135 or best offer. I don’t know if that’s reasonable depends on condition, the carriage from the UK to your location would probably cost a fortune Regards Mike
Thanks Mike, think I have a good one here. Yeah, the shipping across the pond would be awful.
Nice to find a gently ridden and low hour dirt bike of any kind - the way most of them get maintained is awful. Like you said, it would have been nice to know what happened to the rest of the bike because of the condition. My guess is it's climbing hills with a big 4 cylinder in it.
Of course the big bores were not as common and and sometimes the riders were unskilled and lazy (like me), so other than starting, they were fun to torque around on, and were harder to overstress.
Thanks Wayne, yeah, I wasn't hard on my bikes either, was just an average rider and understood if I broke it, I had to fix it.
@montana2strokeracer Oh boy, your 'fix it if you broke it' comment gave me a Hodaka Flashback!
great buy that dale never been down if u ever need a cylinder i have on e you can have it free off charge next video please
Thanks Mark, I appreciate it.
Dale, how much did you pay for the RM 400 engine?
A little more than a dozen eggs.
i seen rust and pitting on the cylinder wall, the only way to make it all right is to rebuild everything as you already know...
Roger that James, that's the fun part you know.
Dale is the man!
strange looks like a mushroom huge barrel/head. makes the transmission case look tiny. im a Suzy fan always wanted a 400 especially the awful 1970.
Hey Frank, oh man that 69 TM400 the orange one, killed and maimed a lot of people.
Here!
Here
I have built 1977,78, 81 82 RM250's 465's parts are there.
Awesome, am still working on a C2 250.
If you think RM400 parts are hard to find try the 1977,78 RM80
Hey Bob, I have heard that, I really didn't think I would ever do the 400 thing again. But I really enjoyed the bike. Got to find a good frame and other needed parts.
Good luck dale.that rm400 will light your fire.i am about 70 percent on a 74 tm250.😂
Thanks James, I am excited to get started on the 400, really need to finish up my 250 first. Good luck finishing up your project.
My previous comment has disappeared?
There’s an RM 400C barrel & head on UK eBay which looks ok and 80.60mm
Might be worth checking out?
Not my item TH-cam!!
Thank you, yeah that would be the 1978 model. My preference is the 79/80 with the long stroke. But there are plenty of folks that prefer the 78 model. Thanks for the heads up. Could be someone will snag it.