3LN1 Carb question

Greetings All,
My name is Blair McIntosh and I am putting together carb kits in Viton for various bikes. If you want to know more about Viton(FKM) then read the documents that in this FAQ <!-- m --><a class="postlink" href="http://www.litetek.co/faq.html">http://www.litetek.co/faq.html</a><!-- m -->
The carburettors on the 3LN1 share many parts with other models so I am going to add it to my list. However the parts book shows what appears to be an o-ring as part of the needle assembly. Can someone confirm if this is the case? I have finished most of the web page for this kit and you can preview it at <!-- m --><a class="postlink" href="http://litetek.co/Carb_Kit_Yamaha_FZR250_3LN1.html">http://litetek.co/Carb_Kit_Yamaha_FZR250_3LN1.html</a><!-- m -->
If you have problems with your motorcycle running too rich then please read the assembly guide under the 'Jet Housing Seal'. This is a critical component on all these BDST type carburettors and it is significant because these seals must be in top condition to stop fuel leaking into the carburettor throat and needle jet (emulsion tube).
The pdf file at the bottom of the page has the Yamaha parts illustration using my part numbers. I have left the needle assembly with the Yamaha diagram number of 34 on it.
cheers
Blair

 

Thanks for your comments and feedback. I need those with product knowledge to help me out in cases like this.
Please correct me if I am wrong, but the part that you mentioned is shown for the 3LN6 and 3LN7 models in the parts book that I have. I am only considering the 3LN1 at the moment because of the overlap with parts that I already have. Also I have limited funds to spend on tooling costs, so I only take on a few new models at a time.
cheers
Blair

 

Hi all,
Well no one seems to know if that needle assembly includes an o-ring.
I have made the carburettor service kit available (Kit A). If it turns out that there is an o-ring lurking in there somewhere then I will do my best to add it later.
At least owners would be able to get most of their parts in one go. <!-- m --><a class="postlink" href="http://www.litetek.co/Carb_Kit_Yamaha_FZR250_3LN1.html">http://www.litetek.co/Carb_Kit_Yamaha_FZR250_3LN1.html</a><!-- m -->
Do not order this kit without carefully checking a parts book and your carburettors to make sure that it suits your bike.
cheers
Blair
LiteTek

 

Hi mate....kit looks good and Ill be using one when I eventually rebuild my carbs.....which wont be for awhile yet unfortunately though (6 months maybe?).......I will let u know about that o ring.
I have a spare set of carbys but they have been half disassembled (and no doubt parts missing) otherwise I would look there for u.

I would post your kits over on this forum also http://2fiftycc.com/index.php as there are a few there with 3LNs

If you are planning on having the inlet manifold rubbers for the 3LN1 ,please let me know.....they are very rare!

 

Thanks Mr GreyImport,
Very nice work on your 250!

I will have the vacuum breather o-ring (original part no: 3LC-1416A-00) available well before you need your kit, and thanks for the offer to check the needle o-ring mystery. Even though your spare carbs are in parts, the needle assembly might still be intact.

Inlet manifold rubbers; always a problem of balancing mould costs. I hate making stuff in NBR also, shelf life issues. I think the only way I could do it is if I could get enough pre-orders to justify my costs. Thanks for the link to the other forum, but I feel like "Mr Spammer" posting about my own gear, any chance you could post a link up for me??
cheers
Blair

 

Thanks! Very funny and good advice.

 

Hi Mr Spammer,

<!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: --> just kidding!

Blair,
Thanx for the compliments on the bike...the old Fizzer came up ok <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->

Now as far as putting up your product on the other forum....Im more than happy to sort that out...the 2 admins are great guys and Im now a mod there also so I will post all the info and links in the Yamaha section.... <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->

Now Ive spent the night looking thru a box and a jar of carby parts......its my first real look into the parts and workings of these carbys ,so take what I say with that in mind!

Firstly the good news is all the choke workings are still intact on the carby bodys .... sent u a PM re the plunger seals <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->

Now heres what I found to do with the needle assembly......as much as there could be missing pieces it looks complete to me?





The green is the plastic part that fits into the end of the spring.
The blue isnt there as the cover already has the bit for the spring to go on built in.
The red? .... I cant even see how they fit into the mix <!-- s:-? --><img src="{SMILIES_PATH}/icon_Eyecrazy.gif" alt=":-?" title="Eye Crazy" /><!-- s:-? -->

I think it was Don mentioned somewhere that the carbs are the same on a YZF750....and going by this parts diagram and no 21 it looks like what I have on my table <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->
http://www.partzilla.com/parts/search/Yamaha/Motorcycle/1994/YZF750RF/CARBURETOR/parts.html

cheers mate

 

Hi Mr Admin Type Bloke,
Thanks for the plug.
Got your pm and will get that away next week.
Well those things in red look like herrings, don't they. I think it will remain a mystery. I think that the diagram might cover the parts that are in another models needle assembly, not the 3LN1
The YZF750 uses push in main jets with o-rings rather than the little square ring on these models. Yours look like this <!-- m --><a class="postlink" href="http://www.litetek.co/Guide_MikuniBDST_MainJetSqRing.html">http://www.litetek.co/Guide_MikuniBDST_ ... qRing.html</a><!-- m -->
Most of the BDST type carbs share a lot of parts but the 250s have a few odd bits. At least the 3LN1 is almost complete so that is a good start.
cheers and thanks for your help
Blair

 

Ok, the diagram in the parts book is labeled, in the lower left corner, as 3LN6010-3010. I am assuming then that this diagram if for a 3LN6. The odd square ring that was mentioned earlier by Dave is for the 3LN6 and 3LN7. So it would appear that the needle assembly that has the o-ring, if that is what it is, is from a 3LN6 or 3LN7. If someone owns one of these and can check this out one day I would appreciate it and it would be good for owners of these bikes too.

On another note, I think I can get the kits together for the 3LN3 and 3LN5 in the not too distant future. They just need a different jet housing seal, part number 3LN-14147-00, compared to the 3LN1 which uses 3LF-14147-00.
cheers
Blair

 

To try to make this clearer I made an online cross reference of the seals for the 3LN models <!-- m --><a class="postlink" href="http://litetek.co/Guide_FZR250Parts.html">http://litetek.co/Guide_FZR250Parts.html</a><!-- m -->
If it turns out that the 6 & 7 models do have an o-ring in the needle assembly then I will add that to the table.
cheers all

 

Thanks for the encouragement Dave.
Speaking of things that are hard to find, have you seen this?
<!-- m --><a class="postlink" href="http://www.atelier-nii.com/motorcycles/catalog/index.html">http://www.atelier-nii.com/motorcycles/ ... index.html</a><!-- m -->
Grab a copy before the web page disappears.

 

Look forward to hearing the news.
Ask your mechanic to check the throttle shaft seals as well. Although it would be signs of running lean if they are leaking, there is no harm in inspecting everything.
cheers
Blair

 

Hi Britt and Nick,
Sounds like you nearly have it sorted. I am no expert on these but you can get a factory supplement for the workshop manual (in Japanese) at Webike.com <!-- m --><a class="postlink" href="http://japan.webike.net/products/9371631.html">http://japan.webike.net/products/9371631.html</a><!-- m -->
Might come in handy.

You have probably checked these already, but it is worth mentioning;
1/The throttle shaft seals - spray some starter fluid or WD40 around the throttle shafts with the engine running and listen for any effect
2/ Valve clearances - Engine will not idle if some are riding
3/ Slide diaphragms - check for holes - they can be small so hold up to the light and stretch a little
Although the BDST carbs are much maligned, I don't think there is anything wrong with them. With your new seals fitted they are just as functional as any other carb and the fact that they have flatslides running in a replaceable housing, rather than wearing out the body itself, has to be seen as a positive.
cheers
Blair