Suzuki GN250 big bore kit to 300cc part 1

Suzuki GN250 big bore kit installation part 1

[@markharris8718]

With the big bore kit the engine does sound and feel like a torquey Royal Enfield 500 I know because I owned one. The big advantage of the gn is that it is very light, well balanced, and very easy to ride well. The other similarity is that people stop me at the petrol station and ask me how old it is, assuming that it is a old ww2 dispatch bike. Job done.

[@john-boywalton2954]

@@markharris8718 Ja, kenne ich,werd auch öfter nach dem Baujahr gefragt... ungläubige Blicke folgen 😁Well done, Brixton!

[@sgntbilco]

I'm glad to know it was the washing machine making the water noise in the bsckground it sounded like hose having a .... Really enjoy your vids, I have a GN 250 project coming soon, so i'm soaking up all your knowledge. 👌

[@marksgemfaceting]

Thanks for watching, glad you are finding this useful.

[@markharris8718]

Hi Moz if you go to eBay.com or eBay USA not your local e bay you will see the gn250 big bore kit for sale and the list of bikes it will fit. The dr250 is listed so I assume it will fit. I can only measure the bore on the old cylinder as the new one is buttoned up. I reckon you will be ok to use the kit just get the USA one if you have any doubts. Good luck and enjoy.

[@markharris8718]

Yes I would if you like playing with engines, I enjoyed doing the job and you do notice a better performance.

[@215alessio]

excellent vid, I am watching and learning. I have bought an 250 gn myself, will upgrade it with a 300 kit but also wit a 17 front and 39 tooth rear chainweel

[@markharris8718]

A very good idea with the rear cog as the engine has plenty of torque. I will do the same myself. Good luck and enjoy the build.

[@olly9172]

Very nice videos, the only things I miss are tea&cookies Sir 😊 Would love to see more of your work. And a little clue comes alongside: Please do not use the torque wrench for loosening the bolts, this could give you headaches when tightening bolts.

[@marksgemfaceting]

Thanks for your interest and comments.

[@philbrown2582]

Hi Mark, Interesting set of videos, could you tell us if the new barrel is taller from the base gasket to the head gasket surfaces or is it the same height as the 250 barrel? Also can you tell us anything about the piston in case it needs to be replaced for any reason? I am thinking that if the barrel is the same height, all you need is a new 300cc piston and a visit to a machine shop! You didn't need to have the crankcase mouth opened out as is needed with some big bore kits apparently, do you have any details of the kit such as part number etc. Kind regards, Phil B.

[@markharris8718]

Thanks for the positive comment.

[@markharris8718]

Hi Glad you enjoyed the vid the measurement you require is 79.1mm

[@moz911]

Hi Mark, great job mate and love the colour. I am restoring a 1985 DR250S at the moment and it runs the same motor without the starter, I am thinking of putting in the Big Bore kit as well. Where did you source it from China? I see plenty on sale at Aliexpress. Cheers mate, keep up the good work. Moz from Oz.

[@markharris8718]

Glad you enjoyed it and the usual issue, when funds allow I will do another. The source was e bay and it was from China and only took 10 days to arrive and quality was fine. Go for it and enjoy.

[@moz911]

@@markharris8718 The bike I am restoring is a DR250 which I think the GN is the same engine. Could you do me a favour and measure the outside diameter of the cylinder barrel so I can check if its the same? I checked Ebay UK and I only see one for sale, what was the name of the guy you got yours from? Cheers Moz from Oz.

[@wayneho340]

Thanks a lot Mr. Harris for this educational video, which is a precious jewel for aspiring bike mechanics. I am currently planning to upgrade the cylinder and piston of a Suzuki Marauder 125. I wonder if I could do it without removing the entire engine from the frame. Thanks in advance. Happy New Year.

[@marksgemfaceting]

Yes you can however it is very easy to remove the engine and once on the bench better to work on and clean. Whatever you do just take your time and enjoy.

[@markharris8718]

If it is the same engine it should be straightforward as all you are really changing is the barrel and piston. You may have to retune the carb a bit assuming it is a carb and not a later injector.

[@1worldgaming18]

i believe it is 292 ccm to be exact with some porting and a bigger carb too should make it run real good for what it is

[@Benjamin-om3ih]

Hi there Mark I'm brand new to this kind of thing but do you think if I follow along with these videos I will be ok? Or do I need a good grounding in mechanics first?

[@markharris8718]

Just do a google search and it will show as eBay USA it comes from China and all fits fine. Good luck.

[@sun6v546]

Happy Wife ... Happy Life . Very good job Mate .... How much was the power Increase ....... ???

[@kridadkool1319]

nothing but love in this video

[@hendradaud8598]

bro, where you can find cylinder block kit for gn300? thank you

[@BrianWader]

What size is that wooden engine frame?

[@RSx94]

Hello (again). The cylinder sleeve is 85mm on these 300cc kits, but do you know how wide the engine block mounting hole where the sleeves goes down in is? If you understand what I mean. I think I'll install a 300cc kit next winter.

[@sahilnaweed7642]

Mr Mark . Need your help brother . How to upgrade 250cc mesin v twin to 300cc . I have motorcycle sym sport v16 but it need to upgrade bcz can't go much fast and I really be proud of u if can help tnx

[@rastalomengo7235]

Hello Mark Harris. Is there necessary any change with the carburator. I liked your videos!

[@marksgemfaceting]

No changes necessary just a clean up and then retune carb

[@30035XD]

How does the GN compare to a RE for example? I own a GN125 but never rode the 250.

[@andrewhoward3264]

I'm in Australia I am going to get a mutt motor cycle with a gn 250 motor I was wondering where you got your bore kit from I no it was from china but who in china thanks I am hoping it fits without splitting the casings thanks

[@marksgemfaceting]

All I can say is that I found it on eBay UK and USA. Many Suzuki bikes use the same basic engine. Just a case of investigation. Good luck.

[@disciplinized7293]

Beautiful GN you have there. I have a GN125 into which i placed a 165cc big bore kit of aliexpress, however im quite dissapointed at the top end performance, although acceleration is much better. Im assuming a bigger carb should help as im running the 125cc carb. You kept the stock carb right? With a 20% increase it should work well but in my case a 30% increase a bigger carb i think is necessary for it to work properly. Btw that colour scheme is beautiful loving the dessert theme

[@markharris8718]

Like you I just enjoy the Challenge keep playing with it and enjoy.

[@stefanoschiro1632]

Hi Mark. I just bought the 300cc for my wife's GZ250. In addition to the mounting specifications of your precious videos, can you tell me if I will also have to change the carburetor jets? Thank you in advance? Stefano da Milano

[@marksgemfaceting]

No need, I played around with different jets it maid very little diffrence

[@stefanoschiro1632]

Thanks Mark. Do you have a Facebook profile?

[@BrianWader]

Im curious how much the whole engine weighs? I squat at work with a junk 91 pound electric motor each week.

[@BrianWader]

I removed my 2005 gz250 engine today and weighed it and was 85 pounds.

[@user-xf4xx3hs2i]

Reparación del motor Sasuke Volti

[@maxizambiasio8924]

top speed?

[@john-boywalton2954]

Naja,denke,wenn mein Moped alt und ausgenudelt ist, würde ich das auch nachrüsten.Aber, prinzipiell reichen mir die originalen 250ccm....und würde das eben nur zur Revision eines alten kaputten Motors nutzen.Tuning finde ich unnötig,da hätte ich mir was größeres kaufen müssen...mir reichen die 17 Pferdchen aus 250ccm....

[@marksgemfaceting]

@@john-boywalton2954 Thanks for being interested

[@john-boywalton2954]

@@marksgemfaceting Normal,plane ja, meine 250er Cromwell so lange zu fahren, bis ich an ner Ampel umfall😁 Bin halt immerhin 59Jahre jung, aber irgendwann lässt einem der Körper im Stich, die Kräfte lassen nach und alles tut weh.Deswegen wird die Cromwell wohl mein letztes Motorrad sein und ich genieße es, solange ich noch kann -aber vielleicht schaffe ich es ja noch bis zur ersten Motorüberholung 😁

[@temistocles19]

would you recommend this engine increase kit?

[@swaggster99]

Hi Mike, where did you get the seat from ?

[@marksgemfaceting]

It’s just the old seat with a seat cover from e bay

[@yavuzkaya632]

Superr 🤗🤗🤗

[@markharris8718]

Will do at work at the moment give me a few hours

[@Ramrum1974]

Hi there, i have the TU 250X and they have the same engine.. Do you think there will be some Problem if i try to upgrade my TU250 X? year 1998

[@markharris8718]

No tool required just align all the marks

[@disciplinized7293]

Btw i didnt have to remove the engine on mine to put in the big bore

[@markharris8718]

Your right, I just enjoy the experience of taking the engine out.

[@polluce82]

@@markharris8718 Hello Mark, I have a 1999 TU250 Volty, I'd like to install the big bore but not all of aliexpress would fit! Some of them require to remachine the casing because the outer barrel of the new cylinder is bigger! Can you measure the outer barrel of the cylinder you removed? That would be really helpful! Awesome job you did with your bike!

[@Monkeyflop]

How long did it take you?

[@letsmakeithapncapn5536]

Okay did anybody else see the door move by itself

[@user-xf4xx3hs2i]

Hollo