Hey guys.. my bike runs okay as it is but my fuel economy is pretty poor. I also notice a fuel smell at the lights. I have thought about buying a jet kit for a while now and just want some advice whether or not to buy this kit.. <!-- m --><a class="postlink" href="http://www.ebay.com/itm/Yamaha-FZR-250R-FZR250-250-R-6-Sigma-Custom-Carburetor-Carb-Stage-1-3-Jet-Kit-/261212237348?pt=Motorcycles_Parts_Accessories&hash=item3cd1766e24&vxp=mtr">http://www.ebay.com/itm/Yamaha-FZR-250R ... 24&vxp=mtr</a><!-- m --> I have an aftermarket air filter which is probs the main cause of my problems and i'm hoping that this company can give me a better setup.. thoughts?
if your fuel economy is poor and you can smell fuel while the bike is running - then you have a richness problem. The aftermarket air filter generally improves flow into a motor, so all things being equal - this will actually lean the mixture out a bit, not make it richer. So I think you can discount the effect of the air filter. The only time you would get a richness problem with an airfilter is if it was really dirty and restricting flow into your motor - this would cause the mixture to become rich. I think you simply have the same problem as a lot of these bikes - same issue I had with my 2KR. The o-rings in your carbies all need to be replaced. The original o-rings deteriorate over time and end up leaking fuel and causing a rich running condition and poor economy. There is a member on the forum - maelstrom. Send him a pm to arrange an o-ring kit to be sent to you. Any bike mechanic can fit this and do a tune-up at the same time. This will help sort out your problem. Getting the carbies balanced properly is also important on these models. If you do a search through the forum for carbie tuning or o-rings - you will find the threads where Blair (maelstrom) has some great advice about the importance of replacing the o-rings in your carbies. <!-- s --><img src="{SMILIES_PATH}/icon_cool.gif" alt="" title="Cool" /><!-- s -->
are you talking about this oring? <!-- m --><a class="postlink" href="http://i174.photobucket.com/albums/w96/coyne12/float.jpg">http://i174.photobucket.com/albums/w96/ ... /float.jpg</a><!-- m --> I have a sync tool so that shouldn't be a problem.
Hi, I am not sure what model you have, so I will cover them all. If you have a 2KR, you should replace the main jet square rings, float needle housing o-rings and pilot screw o-rings. If you have any of the other models you need to add to that list the jet housing seals and the slide housing o-rings. I do not have complete kits for the 2KR finished yet. Though I could sell you the parts you need as the only thing missing will be the float bowl seal. I have complete kits for the others. 2KR <!-- m --><a class="postlink" href="http://litetek.co/Carb_Kit_Yamaha_FZR250_2KR.html">http://litetek.co/Carb_Kit_Yamaha_FZR250_2KR.html</a><!-- m --> 3LN1 <!-- 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 --> 3LN3 & 3LN5 <!-- m --><a class="postlink" href="http://litetek.co/Carb_Kit_Yamaha_FZR250_3LN3.html">http://litetek.co/Carb_Kit_Yamaha_FZR250_3LN3.html</a><!-- m --> If you do not have a 2KR then please read this assembly guide <!-- m --><a class="postlink" href="http://www.litetek.co/Guide_MikuniBDST_JetHousingAssy.html">http://www.litetek.co/Guide_MikuniBDST_ ... gAssy.html</a><!-- m --> it is very important as Mikuni BDST are not like most motorcycle carburettors. Re the jet kit: The only jet that should ever need replacing is the emulsion tube and it has to be replaced along with the needle. Factory Pro have a lot of useful information on their web site. I know nothing about the kits that you found on ebay and I must warn you that replacing your genuine parts with something else may not be a good idea. Secondly the website that you referred to lists the contents of the kit as: Main Jets Needle Adjusters Nylon Spacers Drill Bits for Slide Hole Mod (some models) Idle Mixture Mod Bike Specs Carb Schematic Carb Synchronizer Tool (how to build for $5) Step by step instructions with photos customized to your bike. Which amounts to 4 main jets, some spacers, a couple of drill bits and some instructions. I will leave it to other members of the forum to comment on that since I might be seen as biased. cheers Blair
You can buy Mikuni main jets for $3-5 each at a speed shop. There are very few bikes that need the vacuum port for the slide enlarged; oversizing the port will reduce off-idle response. The 'idle mod' is adjusting your idle mix screws; info is on this site. The DIY carb sync tool is on this site. The 3LN and 2KR have adjustable needles, so the needle shims aren't needed. This isn't the complete waste of money it seems; someone with no carb knowledge will benefit from the 'bike specific' instructions and photos. Anyone frequenting this site doesn't fall into that category, and IMHO should save their money. I will disagree somewhat with Maelstrom's comment about replacing only the needle and emulsion tube; it is often quicker, cheaper, easier to simply replace the pilot / idle jets than attempting to clean them. Main jets are swapped out not due to wear, but rather to change the fueling to match requirements; I don't think this is what he was referring to.
Thanks very much for the replies, all very informative. I will start off by saying I have a 250 3LN3.. My jets are stock, so I shouldn't have a problem there I don't think.. 100 on 1 and 4 and 97.5 on 2-3.. I think my main issue may be float height. Here is my problem: at lights I smell fuel.. I have tried to make it run leaner on idle so I tried turning fuel/air 4 out, if I only go 3 out it seems to bog down at take off and it almost stalls like it is running rich. Then when I take off it doesn't have much power from 4000 to about 9000 but that performance increases when I raise the needle 1 space.. But in doing so I have the same bogging down and stalling issue. This is the reason I thought that kit might be beneficial for me, I'm hoping they will tell me what my float height is and I can get my bike running correct. Any thoughts? Thanks
Your idle screws should be set at around 3 turns out from touching fully in. I'd say your fuel height is way off! Do some digging and rummaging here; the info should be around. Actually, 30 sec on Google netted me this - see if that gives you a starting point that works.
A 3LN3 uses the BDST type Mikunis. After setting your float heights, if you do not get instant results then you should replace all of the seals that I mentioned, especially the jet housing seal. That is the 'A' kit on my site. Without doing that you are wasting your time. Nitrile, what your o-rings are made of, does not last 20 years, so you can safely assume that yours are all rotten. Once you have replaced all of the seals, if you still have a mixture problem, which I seriously doubt, then you can try making adjustments safe in the knowledge that you are not chasing your tail. I am not trying to sell you a kit. I am trying to save you a lot of pain. Visit the Suzuki section on 400 greybike forum and see how many posts and threads there are on carb seals. That is because they have the same type of carbs as your Yamaha. cheers Blair
Thanks again for that information, I think i will rip my carbs apart and start from scratch making sure every single part is nice and clean and make sure every piece of rubber is in tact. dontz125 - that post on that site is actually mine =D same username and stuff.. i should delete it so nobody thinks those settings work.. because they dont XD so yeah.. rip carbs off.. double check everything according to <!-- m --><a class="postlink" href="http://www.google.com.au/imgres?um=1&hl=en&biw=1920&bih=979&tbm=isch&tbnid=0W9g6f-XzOmD-M:&imgrefurl=http://fzr250.com/viewtopic.php%3Ft%3D2977&docid=__wKFG_p2wdABM&imgurl=http://attachments.fzr250.com/HowTo/CarbSpecsFZR250_3LN.jpg&w=938&h=453&ei=AqexUcr1JcyfkwXo2oHICQ&zoom=1&ved=1t:3588,r:2,s:0,i:84&iact=rc&dur=935&page=1&tbnh=156&tbnw=323&start=0&ndsp=45&tx=59&ty=55">http://www.google.com.au/imgres?um=1&hl ... x=59&ty=55</a><!-- m --> and maybe buy some seals if needed. Thanks
Problem: smell of fuel at lights. Low performance at 1/4 throttle to half throttle. Reference: <!-- m --><a class="postlink" href="http://www.mikuni.com/fs-tuning_guide.html">http://www.mikuni.com/fs-tuning_guide.html</a><!-- m --> 1/4 and 3/4 throttle, air/fuel mixtures are controlled by the jet needle and needle jet. Main jet is stock so there is nothing wrong with 3/4 throttle to full. I'll try turning my fuel/air screw 3 out to go back to stock. I'll try lowering my needle jet to center. One thing i am wondering is when you turn the fuel/air out does it allow more air into the mixture or more fuel into the mixture? raising my needle jet to center should richen my mixture up in the mid range obviously improving my mid range performance. if I idle okay at 3 turns out with fuel/air then that setting is fine. If my bike bogs down at the lights and STILL smells like fuel then my floats need to be lowered to decrease fuel in bowels. breaking up all the information really helps.. lets hope I can fix this problem so we can have some sure settings for the 3ln3 on the intergalacticwebs I have this air filter too <!-- m --><a class="postlink" href="http://www.fzr250.com/viewtopic.php?f=8&t=3511">http://www.fzr250.com/viewtopic.php?f=8&t=3511</a><!-- m --> I'm wondering if i'll have to change any settings for this filter to work with a stock carb. do the stock needles have the nylon spacers on them? because mine do.. Here is some good information: <!-- l --><a class="postlink-local" href="http://fzr250.com/viewtopic.php?t=2977">viewtopic.php?t=2977</a><!-- l --> <!-- m --><a class="postlink" href="http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html">http://www.factorypro.com/tech_tuning_p ... gines.html</a><!-- m --> <!-- m --><a class="postlink" href="http://www.fzrarchives.com/ipb/index.php?showtopic=8141">http://www.fzrarchives.com/ipb/index.php?showtopic=8141</a><!-- m --> <!-- m --><a class="postlink" href="http://www.fzr250.com/viewtopic.php?f=20&t=3244">http://www.fzr250.com/viewtopic.php?f=20&t=3244</a><!-- m --> <!-- m --><a class="postlink" href="http://www.youtube.com/watch?v=zm5mB3R8Ucw">http://www.youtube.com/watch?v=zm5mB3R8Ucw</a><!-- m --> PS.. I hate setting float heights!!!! WHY MUST IT BE THE FLOATS <!-- s:bigmachgun: --><img src="{SMILIES_PATH}/th_Big_Machine_Gun.gif" alt=":bigmachgun:" title="Big Machine Gun" /><!-- s:bigmachgun: -->
Adjusting float height is much quicker than fuel height. Set the fuel height for one carb, measure the float height, set the float height on the others, tell everyone else.
just bought the a and b carb seal set for my 3ln3 fzr. man the set arrived REALLY fast thumbs up for that now to get stuck into the carbs thanks maelstrom <!-- s:Biker1: --><img src="{SMILIES_PATH}/th_Biker_1.gif" alt=":Biker1:" title="biker_1" /><!-- s:Biker1: -->
fast kit! Hey blueyedjackel, Where are you? I sold two 3LN3 kits last week. One to Ireland and one to NZ. In any case, if one of them is you that has to be a new record. Edit: I found you in NZ, with full tracking too. Sweet! cheers Blair
